CM1200 Dropping connection intermittently - SYNC Timing Synchronization failure

RCN did check the line and they said they didn't see any issues with the power levels, but they seemed to just reference the levels on this page http://ny.speedtest.rcn.net// which just shows one number for each FwdSNR, Channel Pwr, and Transmit Pwr (not sure where it gets the number for these since there are multiple channels. Maybe its just the average). I did remember when internet was initially set up in my apartment the technician opened a panel in my closet that had some cables behind it specifically the line for my unit then a female to female connector that connects that line to the main room wall jack and another unused line that goes to the master bedroom jack. So I went ahead and connected the modem to the mainline coming into the unit (still using the female to female connector since the line in the wall doesn't go far enough). Power levels look marginally better (See attached) still not within 3.5dbmv. Will try connecting without female to female connector as well to see if that changes the power levels at all. Appreciate all the help.

Connected directly to the line coming into my unit and power looks a little better again. Still a larger range than 3.5dbmv. Will leave this setup for awhile and see if the issue comes back and will report back either way. Appreciate all the help plemans and FURRYe38.

Its getting better. MIght check further back up the line if possible to see if any other splitters/juntions. Or even take a look at the coax line ends to see quality. I've seen some pretty sketchy ones on apartment terminates. 

Well the disconnect has happened a couple more times with the same errors since moving the modem to the line coming into the unit. I took a look at the coax end and it looked fine. At least no obvious signs of damage or corrosion. There aren't any other splitters or junctions that I can see and this is the line coming into my apartment so this is as far as I can test. RCN did test the line up until this point when they initially set up the service and didn't say there were any issues. The power levels still range from -5.5 to 3.3 which is quite a bit more than the 3.5dbmv range you had previously stated. Is there anything else I can do to improve the levels or do I need to go back to RCN with this info?

so you're caught in a catch-22. they've already inspected the line and you're using 3rd party equipment (not from rcn).

So they might charge you to check it again. And the cost of it might be almost the cost of a new modem (unsure how much they charge). 

In my area, comcast bills if the issue is within the home or if its a 3rd party modem. 

So I'd check with rcn to see if they do or don't. 

If they do, and its a higher cost, I'd try buying another modem. Because it could always be the modem but its tough to prove. 

If it turns out to not be the modem, then you can always return it or use it for a backup but it gives you something to tell rcn in that "I've tried 2 different modems and its still giving the same bad data".

If you do buy a new modem, I'd look at the cm1000 or cm1100 and not the cm1200. I seem to see more issues with the cm1200 on here versus the other 2

Instead of buying a new modem. I am going to get the RCN rental one and see if that has the same issues. Then if it does RCN should be able to better troubleshoot the issue. Will update after I have tested the RCN modem.

I've done something similar before. Spectrum wouldn't check the line because I was using 3rd party equipment and they kept saying it wasn't the line. So I rented a modem from them for a month to prove it wasn't a modem issue. So they fixed the line and I went back to my device. 

Not saying that'll happen for you.