I have been using OpenVPN on Archer C7 v5 (latest firmware 1.2.1 from 15 Jul 22). My router's LAN IP range is 10.0.10.0/255.255.0.0.
The router does not have any firewall rules for the LAN IP range (ie any host can talk to any other host); I have IPSec tunneling etc enabled although I don't think this should be important here.

I have configured OpenVPN via UDP or TCP successfully to work for the Internet connections but the connection to the Home network never worked. There are no firewall devices on home network devices that would prevent ping; and no firewall rules for the 10.0 range on the router either.

The VPN range is configured as 10.0.20.0/255.255.255.0. I tried switching between UDP and TCP and even tried adding a manual "advanced routing" config to route 10.0.40.0/255.255.255.0 to 0.0.0.0 but this didn't work either.

The Internet access when using OpenVPN works but I can never ping or reach devices on 10.0.10.0/255.255.0.0

Can anybody help with any suggestions?