It is a little bit difficult to follow.
We need a bit more details to figure it out..
So firstly.. what make and model is your Internet gateway router?
What model is the Extreme? Is it located close to the gateway?
It should be in bridge mode with the wifi active.. which is fine.
What model is the Express? And very important if Gen2 what firmware is it running.. 7.8 is hopeless.. go back to 7.6.8 or 9.
What OS is your computer?
How is IPv6 set on the main router and computer.. this is important because IPv6 is essential and windows recently changed home group settings which messes some things up.
Why not plug the PC into a LAN port on the AE instead of to the gateway/ main router? Is it due to location of items?
So I then un bridged AX and shut off wifi and then connected via Ethernet to my extreme lan port. But the only way the AX shows up and plays music is if I connect to the wifi with my computer.
Now this is the bit I really don't follow.. perhaps due to the multiple meanings of bridge. The Express should still be in bridge mode.. that is router bridge.. not wireless bridge..
When you plug the Express into the Extreme lan port, it should pickup an IP address from the main router same as PC or the Extreme itself. If it is failing then something is wrong. Can you access the main router and check the DHCP or ARP table to find the Express IP address.
Has the Express disappeared from the airport utility in the PC??
If it is still showing then it should still work.. but your IPv6 setting in the Express should be set to link-local only.
