I feel for you guys, im having exactly the same issue. Line drops, sync issues SNR low ( 5-6 ).
Had more than 5 tech guys out.
Every time they pass the line.
Today techy came out, and magic just before he phoned the line was stable SNR sits at 13.
He was here for a good 3 hours, could not find a fault. Replaced indoor wirering, just incase.
All his test passed ect.
1 hour after he left line drops again. So funny.
Phoned him, and he confirmed there was a fault. Finally someone picked up a fault. Nows his coming to replace underground cable tomorrow. Holding thumbs.
Fault been open for 350 hours.
* when he was here his supervisor phoned him like 3 times to make sure his fixing the fault. So thats good atleast.
Will wait and see.