that's what i did.

Hi Frank, can you access internet if clients connected to LAN ports of Archer C7? Try to modify some wireless setttings, like channel.

like i said the problem is DHCP relay - not internet access. Internet works fine, it's just not forwarding DHCP packages correctly to the network so DHCP clients don't get an IP address.

For me it worked, i just disabled DHCP, just ensure that you have settled a gateway and DNS server on DHCP settings, i dont know why but even with disabled DHCP you must put them corectly!

Works fine here as well.

Dhcp disabled and nothing on the WAN.

I've had the same issue with both v1 and my replacement v2 C7. Basically, it seems to be the order in which you do things. The only way I found to fix it once it's stopped working is to do a factory reset and start over. The last time I did that I configured in this order:

Change Wireless 2.4
[*]Change Wireless 5
[*]Change Network - LAN
[*]Disable DHCP


I rebooted after each step. Once thing to note, I use my C7 as a WAP, not a router, so nothing plugged in to WAN port, just LAN port. Assuming you are doing the same. Good Luck.

Old thread, but this IS a problem.
The only fix I've found was firmware downgrade.
See this thread for details :
http://forum.tp-link.com/showthread.php?84834-C7-dhcp-forward-broken-in-bridge-mode-snce-firmware-14110-(131217-works)
good luck!