C5 will not connect to A5 in my lab
Gonna need a lot more info to be of any help:
Are they running the same or similar firmware?
Are you running SRS?
Are you using the same SSID and Password for both devices?
What are your channel and power settings for both devices?
Is this an A5 or A5c? If an A5c what kind of antenna are you using?
Well, just call me stupid. I have discovered an error in the A5 SSID Password. Once I fixed that everything worked just fine.