Intermittent issues can be difficult,let's start with basics.
Type of RG (with IP TV can be 3800, 3801, 3812 aka inid or 589)? How connected to NID, (coax, cat5 ...green port, ethetnet .... red port?
If 3800, 3801 or 3812 can be download http://www.uvrealtime.com/ and post screen shots? If not can you post gateway info from 192.168.1.254
Issue can be outside (cross box, plant, drop, nid) or inside wiring including jack, data cable. How inside wire is ran, not near or crossing fluorescent or CFC lights, or power lines. Grounding issues, electrical surges, microwave usage or treadmill, compressor or motors generating noise on line. Stray voltage on back of tv, ham radio operator, AM radio stations, storms, computer monitor, etc. http://adslm.dohrenburg.net/troubleshoot/interference.php
Effectively noise on line (internal or external), passes a threshold,RG reboots (initialize or retrain). Freezing or pixel is lesser effect, if tech measurements at nid shows no errors on line but have errors at RG, issue inside. If tech measured shows issue at NID then outside.
Uvrealtime may help identify possible suspects.
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