SYNC Timing Synchonization Errors

Hello, after 5 visits xfinity found that a box a few blocks away was under water and fixed my issues for a short while. My internet keeps dropping or is slow and theres no way to get past the help bot. All connections are tight and I keep getting "Sync Timing synchronization failures" and "UCD invalid or channel unstable" failures. Ive gone through 3 modems trying to figure this out. How do I get this resolved? Thinking about moving to T Mobile because I work from home and this has been happening for years with no resolve.