I have very similiar issue. I got Iphone 5 and it and my Ipad stopped ICloud backups on same day (Oct. 15th). It starts to backup and then says "cannot complete". I went into Apple store thinking it was issue with my Icloud account. They connected it and it worked fine. They recommended powering off/on the router which I did, but it didn't work.
Has anybody else been facing this issue and found a solution. Please help, I have tried everything!!!!
It is more than likely the router. I have seen this issue with friends I have with that particular router. I have Comcast/Xfinity, however I have a stand-alone modem that is one of the older ones that does not have a router/wifi built in. I have my modem connected to a different router and have no issues with Comcast/Xfinity Internet.
Have you seen this:
I'm not sure this is the problem, but getting a replacement from Comcast is the way to go. Their modems are notoriously awful, and it's never been a problem to get a replacement. In fact, when the service was upgraded in my area in the last few years, I went through three modems before I got one that worked reliably.
I found a solution
Phone number and describe the problem
I got a call back the next day and a service tesh is on the way Saturday.