Set up glass fibre WAN

I don't live in the US

VLAN 5/4 means VLAN 4 Priority 5.

Yes you are correct, but how to do I route both VLAN 34 and VLAN 4 on the WAN port to my LAN?

I don't live in the US either.

Add two VLANs in the switch, 4 and 34, then make them "tagged" on both the port connected to the modem and the port connected to the TV box. You do not need to connect either of these VLANs to the router CPU since it does not need to see any of the TV traffic.