GoodCloud Site2Site VPN, DNS forwarding

Quick question.

I setup the site2site connection between 2 MV1000 a while ago. I have traffic going from both locations without any issues. However, there is an issues that I have not been able to solve. The DNS. I can ping to a server on the other site, and I can access it via IP. But not via DNS. I tried creating a custom DNS (on the MV1000 from site a) pointing to the DNS (not on the MV1000 from site b) but still it is not working. (I do a nslookup servername dnsfromsiteb it works fine)

So, it is not a connectivity issue, but a configuration one. Any insight appreciated.

Probably edit the hosts list on the sub router (not the server router)