Lumia 635 update problems

[Charles Mickler]

I have a Lumia 635 with Windows 8.1. I have tried several times to install Windows Mobile Insider Preview with no success. The app appears to install but doesn't provide any access to preview builds. Also, when I try to use phone update, I get an error notice saying "We can't look for updates presently, try again later" with the error code 80072f8f; and the backup to the cloud function won't function. It goes to 96% then says "there was an error backing up your settings, try again later" with no error code. The update function wasn't working before I tried to install Windows Insider, and I feel these failures are all related to some program error. I have tried everything except a complete reset, because I can't backup my settings. Any thoughts on a fix for this problem?