Hi, so I've recently purchased a second VR600 Router to replace my Virgin media hub for wireless so I can change settings such as DNS and add VPN options.

Here's a quick diagram for my setup which is easier to explain from.

So if I roam my device from the secondary router to my main one, I can no longer ping the Secondary router or access the DNS server, even if place my extender directly to the main router I cannot access the DNS server, (works fine with any external one so 1.1.1.1 or something to connect to the Internet but that means i can't use the the dns I've setup on Pi hole).

But, if I change the MAC address, I can suddenly access the Pi-Hole, and any other device on the secondary router from the main router, why is this? I did not have any issues like this using my VM Router and the a single archer router in bridge mode.  (although I did have to set the IP/DNS manually I could at least ping the DNS server.

Any help is appreciated, really annoyed. 

Here is the config if that helps.

Virgin Media in Modem Mode

IP: 192.168.100.1

Primary Router (Gateway): 192.168.0.1

DHCP Pool: 192.168.0.2-50

Primary DNS: 192.168.0.50

Secondary Router: 192.168.0.2

In bridge mode