BT SH2 Wifi stops working when I plug in a LAN switch connected to APs

[OliBiard]

I have the following issue.

My set up:

[BT SH2 Router] connected to fibber to the home broadband, supplying Wifi in it's immediate area, with a LAN cable connecting a [Netgear POE Switch], from which two POE LAN cables connect two [Netgear WAX218 Access Points].

I have set up the two [APs] with static IPs that are outside the range of the [BT SH2] DHCP.

I have set up the two [APs] with the same SSID and PW as the [BT SHS] to enable devices to roam across the wifi network.

The issue:

The [BT SH2] Wifi works on it's own but stops working when I plug in the [Switch] => [APs]. The Wifi works well on both [APs]. The Wifi starts working again on the [BT SH2] when I unplug the [Switch] => [APs]. Very frustrating!

I was using this exact set up successfully for a year with the Vodafone router, so imagine it must be a configuration issue.

Any suggestions? Thank you in advance.

[licquorice]

Make sure the SH2 and the 2 APs all use different WiFi channels so they don't conflict with each other.

Giving all your WIFI sources the same SSID doesn't enable roaming, devices will still disconnect from the old signal and re-connect to the new in exactly the same way as if they had different SSIDs.

The other advantage of different SSIDs is that you can force a switch to a stronger signal if a device is hanging on to a weaker signal.

[Crimliar]

Also, make sure your SH2 is not receiving power over its ethernet connection, this can cause issues with some routers that aren't expecting it!

[Keith_Beddoe]

@OliBiard 

I seem to remember this was an old issue with certain versions of the home hub.

Devices that are connected to your access points are seen by the home hub as Ethernet connected devices and not wireless devices.

If a device MAC address is registered as an Ethernet device, then the home hub will fail to recognise it as a wireless connected device until eventually it updates its internal routing, which takes a long time.

A physical disconnection of the Ethernet connection from the home hub seemed to clear this problem, and devices could then connect to the wireless on the home hub. 

At that time there were two versions of the home hub, version A and Version B, made by different manufacturers. I seem to recall it was the version B that had this issue.

I would not be surprised if the issue still exists on the later home hubs.

[OliBiard]

Excellent point, thanks. I've checked and definitely no POE going to the SH2 as the switch has a dedicated non-POE port for the uplink to the router.

[OliBiard]

Very helpful. Thanks.

I've changed the SSIDs, but the issue persists where devices connect fine to AP1 SSID, AP2 SSID, but not to the SH2 SSID.

Could it be a DHCP / setting issue?

[OliBiard]

Interesting. Thanks. Any idea how I can test for this or if there is a fix?

[Keith_Beddoe]

Try it with two different devices. Connect one directly to the home hub wireless, and the other to an access point wireless. If they both work, then swap the two over, and see what happens. You may find that both devices then fail to connect until you interrupt the Ethernet link. 

There is no fix for this issue as its a firmware "feature", but it would be interesting to know whether the SH2 has two versions, and which version you have. 

Other routers do not seem to suffer from this issue.

[OliBiard]

I have tried that.

Nothing seems to be able to connect to the SH2 wifi.

SH2 serial number is: +091298+1909012512

SH2 firmware is: v0.39.01.04077-BT

I wonder if it could be something to do with DHCP/IP allocation, for example:

- Authoritative DHCP on or off? 

- IPv6 ULA enabled or not?

- IPv6 address allocation Stateful, Stateless, Both or Off?

- Wireless mode 1 or 2 or 3?

You're right that I did not have this issue with the Vodafone router at all, working just fine for a year till I switched to BT and the SH2 :(.

[OliBiard]

I've tried multiple combinations of these settings to no avail. Router => Switch => APs is a fairly straight forward / standard network set up so very strange and frustrating that the BT SH2 seems to have this issue and BT don't have guidance on how to set this up (citing they don't support 3 party equipment, which is fair enough, but it's the router settings I need to know about :(). I might just need to switch provider or buy my own router, either way very unfortunate.