Seamless!

The SSID is the name of the network that you connect to, in the list of local networks shown on your PC. It might possibly be 'Plusnet-3X5R' if that's what your current router broadcasts itself as.

The password is the password you type in to connect to that network.

Assuming you're attaching a second router rather than mesh system, the procedure is:

1. Find out the IP address for its control panel - it's printed on it or in the manual. Typically 192.168.1.1 or 192.168.1.254
2. Plug a PC into a LAN socket on this router. Don't plug the PC into any other network, and temporarily turn off its wifi
3. The PC browser should now be able to go to http://192.168.1.1/ or whatever it is
4. Login to the control panel (password usually printed on the casing, or in the manual). Go into the settings
5. In the LAN/network settings, disable DHCP
6. Instead, tell it to use a static IP address - eg 192.168.1.250 Make a note of this address.
7. In the wifi settings, set the network name/SSID to your existing wifi network name
8. In the wifi settings, set the password to your existing wifi password
9. Save settings and reboot the router
10. Plug a LAN port on this router into your switch
11. Turn back on wifi on your PC
12. The router should now form part of the wifi network and devices will roam from one router to the other
13. If you ever need to change the settings on the second router, they're now at http://192.168.1.250/ Theo

Snip!

Crikey Theo! Step by step, it sounds do-able but rather a lot for an agricultural mind to grasp:-)

I'll install the new router and see how the wifi performs. Visitors will just have to reset their devices. Once that is running I'll take a view on the spare router (assuming J. Lewis haven't asked for its return).

Thanks again for your advice on this and to others who have contributed. I'll report back on the outcome.

This rural lane doesn't have copper any more. You may get lucky soon!

Andy