Ethernet, WiFi and 4G

Welcome to this guide to network connections. The HAI-P200-4G controller has two Ethernet ports, a WiFi radio and a 4G modem. This guide explains how to configure each of those links, how the controller picks the one that carries the Internet, and how to share that connection with your equipment.

It all happens in the interface’s Connection menu, which gathers the Ethernet, WiFi, 4G Modem, VPN Tailscale and Connection Test pages.

Prerequisites

• The HAI-P200-4G controller, powered up
• HAI-OS, reachable from a browser (see First connection)
• For 4G: a SIM card with a data plan, and your operator’s settings (APN, and a PIN code if applicable)

Overview

Link	Name in the interface	Role	Factory configuration
Ethernet, upper port	eth0	Company network, wired Internet output	DHCP
Ethernet, lower port	eth1	Local machine network: PLC, maintenance PC	Static IP 192.168.1.16, mask 255.255.255.0
WiFi	wlan0	Client of an existing WiFi network, or access point	Client mode, no network remembered
4G	wwan0	Mobile Internet, backup or main	Disabled

Tip

The two Ethernet ports are independent: no traffic passes from one to the other until you enable the connection sharing described below. A PLC plugged into eth1 therefore stays isolated from the company network.

How the controller picks its Internet output

Several links can be active at once. Every 15 seconds, the controller checks which one really gives access to the Internet, by sending a ping through each link, in this order of preference:

1. Ethernet eth0
2. Ethernet eth1
3. WiFi wlan0
4. 4G wwan0

The first link that answers carries the controller’s Internet traffic. In practice:

• A cable plugged into a network with no Internet (a PLC’s network, for example) is never chosen, even if it is “connected”.
• 4G is only used if nothing else answers. As long as a wired or WiFi link works, it is not even tested: this mechanism uses no mobile data.
• An unplugged cable is detected in about a second, and the switchover is immediate.
• When a higher-priority link comes back, the controller waits for two successful checks in a row before switching back to it, to avoid flapping on a failing cable.
• A link that stops answering is abandoned after three consecutive failures, that is, about 45 seconds.

The local networks stay reachable throughout: a port connected to a PLC keeps talking to it, whether or not it carries the Internet output.

Note

The order of preference cannot be changed from the interface. The first evaluation happens about 25 seconds after start-up.

The footer icons

At the bottom of every page, three icons sum up the state of the links, refreshed every 10 seconds:

• WiFi: green when the controller is connected to a WiFi network. It takes the shape of a broadcast antenna when the access point is running.
• 4G: orange when the mobile connection is established.
• VPN: green when Tailscale is connected.

Ethernet

Go to Connection > Ethernet. The page shows one card per port: Interface eth0 and Interface eth1.

Reading a port’s state

At the top of each card:

• Cable connected (green) or No cable connected (red) tells you whether a cable is physically present, refreshed every 3 seconds. Status unknown means the port is not seen by the system.
• The Internet output badge appears on the port that currently carries the controller’s Internet output.
• MAC Address: the port’s hardware address, useful for a DHCP reservation on your network.
• In DHCP mode, the Active DHCP Configuration block shows the address actually obtained: IP Address, Subnet Mask, Gateway, DNS.

Tip

A connected cable does not mean the Internet goes through that port: the Internet output badge is what says so. On a port connected to a PLC, the absence of that badge is normal.

Configuring a port for DHCP

1. In Configuration Mode, choose DHCP. The address fields grey out.
2. Click Apply.

The port restarts and asks the network for an address. The Configuration applied for eth0. notification confirms the operation, and the Active DHCP Configuration block updates.

Configuring a port with a static IP

1. In Configuration Mode, choose Static IP.
2. Fill in IP Address, Subnet Mask, Gateway and DNS. Several DNS servers can be entered, separated by commas. The gateway and the DNS servers are optional.
3. Click Apply.

The change is applied immediately, with no controller restart. If the values are refused, the Failed to apply configuration for eth0. notification appears: check the format of the addresses.

Caution

If you change the address of the port you are connected through, the page will stop answering: the port restarts with its new address. Reconnect on that new address, after adapting your PC’s network configuration if needed.

Caution

An addressing conflict to be aware of. The eth1 port ships on 192.168.1.16/24, and 192.168.1.0/24 is also the most widespread addressing plan among operators and companies. If eth0 gets an address on that same network, both ports claim the same subnet: routing becomes inconsistent, and connection sharing to eth1 stops working properly. In that case, move eth1 to another network (192.168.10.16 / 255.255.255.0, for example) and reconfigure the equipment connected to it.

Note

Every Ethernet configuration change, accepted or refused, is recorded in the controller’s audit log with the chosen mode, the address and the gateway. That log is exported from Security > Audit & Logs (Download the audit logs).

Sharing the eth0 connection to eth1

The controller can act as a router for the equipment plugged into eth1, giving it Internet access through eth0. Under the Interface eth0 card:

1. Turn on the Enable connection sharing switch.
2. Click the APPLY button just below it (distinct from the Apply button of the address configuration).

On the equipment side, configure a static IP address on eth1’s network, with the controller as the gateway and the DNS server. With the factory configuration:

Equipment setting	Value
IP address	192.168.1.x (other than .16)
Mask	255.255.255.0
Gateway	192.168.1.16
DNS	192.168.1.16

Caution

The controller does not hand out IP addresses on eth1: it only relays DNS requests. A device using DHCP on eth1 will get no address. Configure it with a static IP.

Sharing is restored automatically at every start-up, even if the source link takes a while to come up. Only one source can be shared to eth1 at a time: enabling sharing from eth0 disables any sharing from WiFi or 4G, and the switch greys out with the mention (Disabled: sharing on WiFi active) or (Disabled: sharing on 4G active) when another sharing is active.

Note

A WiFi access point that also shares an Internet connection is incompatible with this sharing: it is then stopped, and the interface tells you so (WiFi access point stopped: it cannot run while eth0 shares its connection to eth1.). An access point without an Internet source (None) can run alongside it. See WiFi access point.

Tip

If the equipment on eth1 loses its Internet access after the source link goes down, re-apply the sharing with APPLY.

WiFi (Client mode)

Go to Connection > WiFi. The selector at the top of the page switches between Client (the controller joins an existing WiFi network) and Hotspot (the controller broadcasts its own network). This guide covers Client mode; Hotspot mode has its own guide, WiFi access point.

Connecting to a WiFi network

1. If the radio is off (Radio Off status), tick Enable WiFi Radio then click APPLY. The list of networks appears.
2. Click the refresh button to the right of Detected SSIDs to scan for networks. The Scan completed: N network(s) found. notification confirms the scan.
3. Select your network in Detected SSIDs. For a hidden network, choose Other and type its name in Enter SSID manually.
4. Type the password in Password.
5. Click APPLY.

The Connected to notification confirms the connection. The status changes to Connected, the signal bar is shown as a percentage, and the Active WiFi Configuration block gives the network (Connected to), the IP Address, the Subnet Mask, the Gateway and the DNS obtained.

Note

There is no static address setting for WiFi: the address is assigned by the network joined. The network is remembered, and the controller reconnects to it by itself at start-up.

Tip

To rejoin a network already known, there is no need to type the password again: select the network and click APPLY, and the stored password is reused.

Changing network or disconnecting

While the controller is connected, the connection fields are hidden.

• Disconnecting: click APPLY. The controller leaves the network (Disconnected from WiFi) and the list of networks reappears; you can then choose another one.
• Turning the radio off: untick Enable WiFi Radio then click APPLY (WiFi radio disabled and disconnected).

Client or Hotspot: a single radio

The controller has only one WiFi radio: it cannot be a client of a network and an access point at the same time.

• Connecting to a network while the access point is running stops the access point.
• Moving the selector from Hotspot to Client stops the access point and puts the controller back on its remembered network (Access point stopped: wlan0 is back on its WiFi network.). If it has no remembered network, the list of networks is refreshed so you can choose one (Access point stopped. Select a network to reconnect wlan0.).

Caution

If the controller reaches the Internet over WiFi only, switching to Hotspot cuts that access. Make sure you have another way in (Ethernet, 4G or Tailscale) before switching.

Sharing the WiFi connection to eth1

Under the Client card, the Enable connection sharing switch, followed by its APPLY button, shares the Internet of the WiFi network joined with the equipment plugged into eth1. The behaviour and the equipment configuration are the same as for sharing from eth0.

That sharing keeps the radio in client mode: the access point then becomes unavailable, and the Hotspot selector greys out with the message Hotspot unavailable: wlan0 is used as a WiFi client sharing its connection to eth1. Disable that share to use the access point.

4G

Go to Connection > 4G Modem.

Reading the modem’s state

Status	Meaning
Checking…	The page is querying the modem.
No SIM	No SIM card detected. Every setting is disabled.
Disconnected	The mobile connection is not established.
Connecting…	The modem is attached to the operator’s network, but the Internet does not answer through it yet.
Connected	The Internet answers through the modem.

Once the connection is established, the page shows the Technology (lte, for example), the Operator and the signal quality as a percentage. The state is refreshed every 5 seconds.

Note

With no SIM card, the page shows No SIM card detected — insert one and 4G restarts on its own within 15 minutes, or reboot to pick it up now. The controller checks for a card every 15 minutes; a restart picks it up immediately.

Enabling 4G

1. Fill in the APN given by your operator. This field is required.
2. If the SIM card is protected, type its PIN Code.
3. If your operator requires it, fill in User and Password. Those fields stay empty in most cases.
4. Tick Activate Modem.
5. Click Apply.

The connection takes from a few seconds to a minute. The notifications follow one another: Connecting modem… Please wait, then Modem connected (nmcli). Validating connectivity…, and finally Modem connected successfully. when the Internet answers through the modem.

If the mobile connection is established but the Internet does not answer yet, the Modem connected, but nothing answered through it yet. The card stays enabled — check the APN and the subscription, or give the network a moment to attach. notification appears. 4G stays enabled: the network can take a while to attach, and the state will update by itself.

Caution

The interface says so under the Apply button: after any change to the modem’s settings, a full power restart of the controller is required (cut the power, then restore it).

Tip

The APN, PIN, User and Password fields are saved as soon as you click Apply, even if the connection fails. On a failure, the Activate Modem box unticks itself: correct the setting at fault and start again.

Possible error messages:

Message	Meaning and action
Please enter an APN	The APN field is empty.
Wrong PIN code !	The PIN code is refused by the SIM card.
No SIM card detected. The modem reports an empty slot — check that the card is fully inserted, the right way round, and in slot 1.	The card is not detected: check that it is inserted and the right way round.
No mobile device detected yet. The modem may still be starting up — try again in a minute.	The 4G module has not finished starting up. Try again in a minute.
The modem is in a failed state and cannot connect. See the Modem log for the reason reported by the module.	The 4G module is in a fault state. Check the SIM card, then power-cycle the controller.
Modem connection failed (nmcli).	The operator refused the connection. Check the APN, the credentials and the subscription.

Disabling 4G

Untick Activate Modem, then click Apply. The Modem disconnected. notification confirms the shutdown.

Modem monitoring and automatic restart

Once 4G is enabled, the controller monitors the connection every minute: is the mobile connection established, and does the Internet answer through the modem?

• If the mobile connection drops, the controller re-establishes it by itself, in three attempts 30 seconds apart.
• If those attempts fail, or if the connection stays established without the Internet answering for too long, the 4G module is power-restarted (by cutting its reset line), provided the option below is active.

Two settings drive that restart:

• Restart the modem when the internet connection is lost: active by default. A ? icon next to it explains how it works.
• Wait this long before restarting (minutes): how long without Internet before the module is restarted, from 1 to 240 minutes. Default: 10 minutes.

The module’s restart obeys a few safeguards:

• never during an alarm voice call;
• never in the first four minutes after the controller starts, to give the module time to attach to the network;
• an increasing delay between two restarts: 5 minutes after the first, then double each time, up to 30 minutes. That counter goes back to zero as soon as the connection returns.

Tip

A single lost ping is not treated as a failure: it takes two missed checks in a row, that is, two minutes, for the link to be reported as degraded. And a SIM card whose data plan is exhausted will not cause a restart loop: the increasing delay prevents it.

The box’s 4G indicator

The 4G indicator on the front panel reflects the monitored state:

Indicator	Meaning
Off	No mobile connection, or 4G disabled.
Blinking	Mobile connection established, but the Internet does not answer (or no longer answers) through the modem.
Steady on	4G connection with a working Internet.

Sharing 4G to eth1

Under the modem’s settings, the Enable connection sharing switch, followed by its APPLY button, shares the mobile connection with the equipment plugged into eth1. The behaviour and the equipment configuration are the same as for sharing from eth0. Sharing is restored at start-up, including when the modem takes a while to attach: it is enabled as soon as the mobile connection is available.

Caution

With this sharing, all the Internet traffic of the equipment on eth1 goes through your mobile plan. On a capped subscription, check what that equipment exchanges.

Reaching the interface remotely over 4G

Caution

The controller’s web interface never answers on the 4G link, even with a SIM card holding a public IP address: the firewall reserves the interface for the local networks and the VPN. To reach the controller remotely through 4G, use the Tailscale VPN.

Approximate location

The Approximate location card, at the bottom of the page, estimates the controller’s position from the 4G cell it is connected to. This is not a GPS: the position is that of the cell tower, with an error of a few hundred metres to a kilometre.

• Turn on Estimate location from the 4G cell. The search starts immediately.
• The Refresh button runs a new estimation; the Open in OpenStreetMap link opens the position in a browser, and a map is shown on the page.
• The position is also shown on the home page.

This feature is disabled by default: when it is active, the cell’s identifiers (operator, area and tower identifier) are sent to an external location database. No personal data leaves the controller.

Note

If the No position: the modem must be connected, and the cell must be known to the location database. notification appears, either 4G is not connected or the cell tower is not referenced. Try again with Refresh once 4G is connected.

Testing a link: Connection Test

The Connection > Connection Test page measures a link’s quality with a ping test: latency, jitter and packet loss.

1. Choose the target in Target: Google DNS (8.8.8.8), Cloudflare DNS (1.1.1.1), Google (google.com), Network gateway (the gateway currently in use) or Custom target… to type an address or a host name.
2. Choose the link in Network interface: Automatic lets the controller use its current Internet output, or force eth0, eth1, wlan0 or wwan0.
3. Choose the length in Test length: Quick (5 packets), Standard (10 packets) or Thorough (20 packets).
4. Click Run test. The Stop button interrupts a test in progress.

The results show a quality banner, the Packet loss, the Avg, Min and Max latencies, the Jitter, a curve of the response times and, under Detailed output, the test’s raw output.

Tip

Select wwan0 explicitly to test 4G while Ethernet carries the Internet: it is the only way to check the backup link without unplugging the cable. Test Network gateway to tell a local problem (the gateway does not answer) from an Internet access problem.

Troubleshooting

Symptom	Likely cause and action
Cable connected but no Internet output badge	The network connected has no gateway, or does not reach the Internet. Normal for a PLC network. Test the link in Connection Test with the interface forced.
The Ethernet page stops answering after Apply	You changed the address of the port you were connected through. Reconnect on the new address.
A device on eth1 has no Internet	Check that sharing is enabled on a single source, that the device has a static IP with the controller as gateway and DNS, and that eth0 is not on the same subnet as eth1. Re-apply the sharing with APPLY.
Connection failed (WiFi)	Wrong password, or network out of range. Run another scan and check the signal level.
No WiFi network found.	No network detected. Check the antenna and the range, then scan again.
Access point still running on wlan0: stop it to scan for networks.	The access point is running: move the selector to Client to stop it before scanning for networks.
Failed to enable WiFi radio	The radio could not switch on. Try again; if the problem persists, restart the controller.
A Connecting… status that persists (4G)	The modem is attached to the network but the Internet does not answer: wrong APN, data plan exhausted or not activated. If the automatic restart is active, the module is restarted once the configured delay has passed.
A No SIM status although a card is inserted	Card badly inserted or the wrong way round. Reinsert it, then restart the controller for immediate detection.
The 4G indicator blinks permanently	Mobile connection established with no Internet. Same diagnosis as Connecting….
The interface is unreachable at the SIM’s IP address	Normal behaviour: the interface does not answer over 4G. Use the Tailscale VPN.