On Demand running Amok

I have 2 non X1 boxes. For at least the last 2-3 months my On Demand has been running amok, with both boxes exhibiting the same issues. It will either not let me tune in to OD at all, or if I get on and try selections it won't let me actually choose, with the "sorry you're having trouble" or try checking plugs or unplug-replug, etc then kicking me off. (I've checked connections, unplugged-replugged multiple times to no avail and tried refreshes). I'm also getting audio but no video, or audio out of sync with video, getting kicked off mid-view then most times not able to reconnect; or fast forward and reverse running amok, controls freezing, at which point my only alternative is to power off in hopes-- not always successful-- of starting completely from scratch. Anyone else going through this? I can't get to an xfinity store to exchange both boxes, and even if I could I'm not convinced exchanges would fix the issues since I fear the problem is systemic and not caused by my boxes. Again, has anyone encountered these problems and found satisfactory resolution?