Cant connect to anything via VPN?

It's DNS.

Clients were connecting fine via VPN. Successful authorization.However they couldn't access anything in the network or access internet. Turns out the DNS servers the clients were assigned after login were not responding. Me being the smartass send a screenshot of telnet to port 53 timing out. Then one of the senior engineers reminded that you cant use a tcp service to check udp port.

TIL:- That DNS works on udp port 53 and tcp port 53 is used for zone transfer and other exotic stuff.