The last released firmware version was 7.7.3 – April 2014. The next firmware release should include the fix, so Apple Support can better advise you. We have not been provided with a date, nor a guarantee that the fix is available however we have strong release to believe it will be included as we have worked with Apple on this specific matter.
I used a previous airport..the flat one not the taller version available now… for wifi and used an ethernet cable to directly connect to the cable company router with a static IP for port forwarding and it worked well.
Currently the supplied router (Cisco) from the cable company has lousy wifi so wanted to revert to what I had done previously at another location. Use the cable router for signal and use the airport for wifi.