@gadgetgeek2000 @kinoCharlino
SNR is very important, for QAM256, you need at least 30dB to get a lock on the modulation. But it’s recommended to have at least 33dB. For QAM64, you need at least 24dB, but it’s recommended to have at least 27dB.
But it’s not the only factor that can affect reception. The second is the channel power level. You need to be between -15dBmV and +15 dBmV (That apply to QAM, for OTA, the ATSC specs is different). Normally, cable operators wants it to be right in the middle. There is also a third one, the total power entering your tuner (too much power will cause the tuner to overload). This one is more difficult to calculate without a spectrum analyzer. But if the cable operator installer did his job properly, it shouldn’t be a problem.
I would recommend also that you inspect your cable. Make sure that the shielding is not exposed. Also, make sure that the connectors are all well tighten. Loose connector can cause brief signal breaks and let RFI in. Also, RFI can comes from the cable operator network. MSOs track down those interference, but sometimes it can take time to find.
For OTA reception, well that can get difficult quickly. OTA needs to deal with multipath interference, adjacent channel interference, co-channel interference, impulse RFI caused by appliances like refrigerator, air conditioning, LED light, etc. You can have a perfect signal, but your air conditioning unit starts or stops and creates RFI for a split second. This is called impulse noise interference. Those are a nightmare to track down and eliminate.
Sure, RF issues are the most common problem causing errors in the transport stream. But there are several other causes that can create errors in the transport stream that we, as an user, have no control over. It could be cause by the cable operator and the broadcaster itself. For example, the other day I was recording with plex and an Amber Alert message cause plex to abort the recording. The alert message insertion caused several issues in the transport stream. there were discontinuity counters errors, PCR errors, in the TS stream.
In the broadcast world, errors in the transport streams happen all the times. The system was designed to be errors tolerant and mpeg-ts has been designed that way. PlexDVR must be error tolerant also. You can tell your users to get better hardware, to track down interference, to position the antenna to another position. That are great advises. We need to have the best reception as possible. But all that is not enough if plexDVR is not error tolerant. Even with the best RF reception possible, errors will happen. It could be a thunder storm, it could be a bad advertisement insertion or an Alert message insertion causing discontinuity counter errors, it could be a bad edge QAM generator at the cable operator head end. Errors will happen and plex need to deal with it. Otherwise plexDVR will not be reliable.
Just my 2 cents as a DVR user. 
