Hi all and happy New Year everyone
I have a Vigor 2820 through a BT POTS modem on the WAN port and I am using a TP link N600 to give me Wi-fi and additional ports and better Wi-fi as it's a fairly big house. I have spent some time abroad so everything was disconnected before I left, as it worked before I expected it to work when I reconnected it. Config backed up on desktop which died just after I got home! I can get on both routers and wi-fi works on the N600 but wont allow internet connection, although I can connect to the internet by cable on the 2820. The problem seems to be communication between the N600 by Wifi and the 2820. I don't recall setting up any specific routing between the 2 of them before but would welcome any suggestions,
Kind regards
Brian

I'm not entirely sure what a "TP Link N600" is...is it Wireless Router being used as an Access Point? (i.e with its WAN disconnected, DHCP server turned off) and connected LAN port-to-LAN port with the 2820?

If so, you've given it a static IP address, in order to manage it (because it's unlikely to have a DHCP Client for its LAN side). Can you ping it via the wired network?. If you connect a client to it via Wifi, does that client get an IP address? (from a DHCP server on the 2820 maybe?). Can the client ping the "TP Link N600"?. Can the client ping the 2820?
What does a 'Tracert/traceroute' to a target on the internet (eg 8.8.8.8 ) show?

and, er, what's a "BT POTS modem"?

Thanks for the quick reply hornbyp,
You are correct in assuming the N600 is being used as an access point but it is also being used as the DHCP server. It is configured on 192.168.1.2 with the 2820 on 192.168.1.1, with the WAN interface on, which may be the problem. It is on a static address, and with wifi on the client gets an IP address. I didnt try a tracert but I can't ping the external network at all, or the 2820, although they are on the same network subnet. Unfortunately the rest of the family need internet access for smart TVs, laptops, and mobile phones so my time to test is limited! As soon as I can disconnect the existing BT hub I am going to try it using the TP link for wifi only, disabling DHCP although I can't disable the WAN interface, then connecting it to the 2820 as the router and DHCP server. Finally my apologies for using an abbreviation BT POTS is a British Telecom Plain Old Telephone Service modem! All I have to do now is wait until the rest of the family are ok with a brief loss of service, and will post the answer as soon as I have solved the problem.

briandalby wrote:
You are correct in assuming the N600 is being used as an access point but it is also being used as the DHCP server. It is configured on 192.168.1.2 with the 2820 on 192.168.1.1, with the WAN interface on, which may be the problem. It is on a static address, and with wifi on the client gets an IP address.

There aren't two DHCP servers in this setup are there? ... or static IP addresses that haven't been excluded from DHCP ranges, maybe?

my apologies for using an abbreviation BT POTS is a British Telecom Plain Old Telephone Service modem!

Yes, that was my definition of POTS modem as well, but I couldn't for the life of me, see how you'd connected one to the 2820.
Is it one of these, by any chance? https://www.draytek.co.uk/products/legacy/analogue-backup (which I'd never come across before today!)

Which device is providing the Internet connection? If it's the 2820, is the DHCP server on the N600 specifying the 2820 as the Default Gateway (rather than itself) :?:

Last person in the UK still using a dial-up connection? :lol: