This topic

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

OliBiard — Wed, 14 Jun 2023 15:34:22 GMT

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.

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

licquorice — Wed, 14 Jun 2023 16:01:45 GMT

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.

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

Crimliar — Wed, 14 Jun 2023 20:23:46 GMT

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!

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

Keith_Beddoe — Thu, 15 Jun 2023 07:43:59 GMT

@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.

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

OliBiard — Thu, 15 Jun 2023 07:53:44 GMT

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.

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

OliBiard — Thu, 15 Jun 2023 07:55:17 GMT

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?

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

OliBiard — Thu, 15 Jun 2023 07:56:13 GMT

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

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

Keith_Beddoe — Thu, 15 Jun 2023 08:19:36 GMT

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.

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

OliBiard — Thu, 15 Jun 2023 09:47:56 GMT

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 :(.

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

OliBiard — Thu, 15 Jun 2023 13:34:55 GMT

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.

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

licquorice — Thu, 15 Jun 2023 13:44:54 GMT

There are no router settings you can make on the SH2 that will have any effect.

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

licquorice — Thu, 15 Jun 2023 13:48:22 GMT

Does the hub Wifi stop working when you connect just the switch with no APs connected?

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

licquorice — Thu, 15 Jun 2023 14:12:59 GMT

Do the other Ethernet ports on the hub stop working as well as the WiFi?

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

OliBiard — Tue, 27 Jun 2023 09:24:54 GMT

Thanks for all the advice everyone!

I've tried it all and then some -- ethernet etc. Seems it's just the wifi that is affected.

In the end I have resolved this by getting my own router. Cost £60 for a good one. That's £60 I did not want to have to spend, and seems a real shame that BT don't provide better information or support on how these things can be set up on their equipment, but at least now I have exactly what I need and it works a treat.

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

Crimliar — Tue, 27 Jun 2023 10:07:56 GMT

I guess I'm curious as to what "good" router you managed to get for £60? Also how were you testing that the WiFi on the SH2 was down? Remember that 5GHz WiFi on DFS channels can drop for up to 10 minutes when you change any settings - while it checks the selected channels are clear!