if you tried straight from tap and different modems,and still the same, too much noise in line. could also be the tap or drop. you didn't say if you used a temp drop or the same drop. what system are you in? charter was really bad about sync and pulling ip and still not working. i have also had backfeed through ground to cause same thing, very rare, normally will not sync if it's the ground, but few times have been same as your problem. your laptop i take it is good, so that rules out the computer.
This is CABL.com posting #173934. Tiny Link: cabl.co/mTpy