I have comcast connection. Modem - SB5101U.
Below are the list of S/N ratio at 3 different instance of time.
Frequency 397750000 Hz
Signal To Noise Ratio 42.6 dB
Power Level 24.8 dBmV

Frequency 681000000 Hz
Signal To Noise Ratio 17.4 dB
Power Level 22.6 dBmV

Frequency 469750000 Hz
Signal To Noise Ratio 23.4 dB
Power Level 21.8 dBmV

Acquire Downstream Channel In Progress
Cable Modem Status Offline

Restarted the modem, router, but i could see only Power and PC activity lights in modem solid, receive is having blinking lights.

I checked the logs and i have the below two message coming up frequently. Date seem to have moved back, guess the modem is using the default date.

1/1/1970 0:01 3-Critical T001.0 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing
1/1/1970 0:00 6-Notice M571.1 Ethernet link up - ready to pass packets

Please let me know if this is modem issue or cable issue??