1 Gbps EE broadband : use router only as access point

[planetf1b]

I'm considering getting the 900/110 service on EE broadband. 

I already have a router (N100 miniPC running opnsense) that I will continue using as router since I run a number of things on there including packet inspection etc.

Can the BT provided router be used purely as an access point bridged to an existing network (over ethernet)?

I currently use my existing ISP provided eero (they're horrid for routing, but decent for wifi), but need to return if I switch. 

Obviously I will otherwise buy a standalone wap system -such as https://ui.com/wifi but extra £ 😞

[XRaySpeX]

@Mr_Incredible : Other than the SSID & pwd of the SH+ Guest Network there are no DHCP settings anywhere in the router for it. I connected to the Guest network of my SH+, with default DHCP, & found it had a Gateway IP of 10.100.100.1 & had assigned my PC to 10.100.100.196. However there was no trace of this connection within Advanced Settings > My Network.

EDIT: The last statement is not quite true! Before I connect my PC to the Guest Network there are no WiFi connections in My Network. After I connect to Guest Network by WiFi an entry appears in the WiFi connections in My Network, but it's not 10.100.100.196. It is in fact 192.168.1.9 which is the reserved (Static if you like) IP I give to my PC over WiFi. What do you make of that? Does it mean its IP over the Guest Network, 10.100.100.196, is synonymous with its main network IP, 192.168.1.9?

Further observations:

• I can ping 10.100.100.196 from my PC.
• When I ping 192.168.1.9 I get:

Pinging 192.168.1.9 with 32 bytes of data:
Reply from 192.168.1.10: Destination host unreachable.
Reply from 192.168.1.10: Destination host unreachable.
Reply from 192.168.1.10: Destination host unreachable.
Reply from 192.168.1.10: Destination host unreachable.

where 192.168.1.10 is the reserved IP I give to my PC over Ethernet.

I shall do further tests to what isolation there is.

[Mr_Incredible]

@XRaySpeX  Crikey!

When I connect my S22 Ultra to the guest wifi  it gets a 10.100.100.0/24 address.  However, I assume because it uses a randomised MAC address, I don't think it can be associated with any previous IP to the 192.168.1.0/23 subnet.

FWIW, I cannot ping from my PC to the S22 nor vice versa when connected to the guest wifi.

If I set my phone's wifi connections to both the guest wifi and main wifi to have my phone's MAC address instead of random and  then connecting to the main wifi first, the guest wifi does assign the same local link address to both connections but the 10.100.100.0/24 wifi connection is definitely still isolated from the main as I cannot ping between my PC and the phone when on Guest Wifi.

Perhaps there are some firewall rules you  have lurking in the background somewhere that allows you to ping between subnets?

[Mr_Incredible]

As a follow up to this, I put another 3rd party router into the mix to connect to the ONT and plumbed the SH2 back in as an AP just by connecting a LAN port to the 'new' router.  The WAN port remained unconnected. 

Although the 2.4Ghz, 5Ghz and 'compatible' WiFi networks all work and connect to the internet via the new router as expected by the LAN port (and by using a DNS and DHCP server on Adguard running in a container on Proxmox elsewhere on the network!) the Guest WiFi appears to be bridged directly to the WAN port and I assume the Guest WiFi takes  that as  its default because when connected to Guest there was no internet at all.  I even manually changed the WiFi settings on the phone and manually set an IP, Gateway DNS, the WiFi would not connect me.

So the SH2 cannot provide a Guest WiFi if plumbed in as a 'dumb' AP point because nothing can be done about the WAN port/Gateway and DHCP working on that interface, i.e. 10.100.100.0/24.

I need to get out more......

[JimM11]

@Mr_Incredible But if they let you out more, then this information that you find would not be forthcoming! You will never be truly sure as there are no AP/BRIDGE modes etc so at the mercy of how the FW controls..