Fitbit has a message that Comcast/Xfinity is having issues sync/setting up Aria. The fix they sent, I can't follow. I don't know where to find "additional setting" and click on 2.4 frequency when I am in my account. Will you provide me with a fix please? I already did a restart on my modem but that didn't help.
Based on a web search, the OP's question seems to stem from this thread:
That might get you somewhere.
There is also this newer (and much shorter) thread: