AC1200

you didn't give us much to go off. 

1. you have the R6220?

2. what firmware is on it?

3. what modem/gateway is it connected to? 

4. whats actually happening? "looses transmission" doesn't tell us much. Does it stop broadcasting? Does it broadcast but you can't connect to it? Does it say "connected, no internet"? Do wired devices drop?  What is actually going on in details. We're not there to see it so we need accurate descriptions to try to help you