If the 3 or 4 cable boxes were exchanged over a long period of time, then you've been very unlucky. But if you exchanged all of them within a short period of time to fix corrupted recorded programs, it's more likely that you have a signal issue. You should schedule a tech visit to check your signal strength, including at the tap. If your cable comes in from a pole, be sure to specify when scheduling the appointment that you need a tech with a ladder.
The first few exchanges were within months of each other. Some of the techs that came out were aware that the Contour 1 Cisco boxes were prone to getting error code 126.96.36.199 and other corruption issues. In cases where a playback worked once, but failed later, that would not have been a signal issue, since it had played back correctly once. I've been told that the Contour 2 versions of the Cisco boxes may fix the corruption issue.
It's possible you've had 3 or 4 bad boxes, but it's unlikely. Typically when people exchange cable boxes several times, they later find there was a signal issue. An error can occur during playback of a recorded program that's been watched before. When you press a key on the remote to pause, FF, reverse, etc., the remote sends a command to a Cox server. When a signal issue is occurring, the DVR waits for a response it never receives. A signal issue during recording will cause an error at that point during playback.
I've personally experienced erroneously reported recording times of over a thousand minutes. The cause was found to be a main line signal issue. When that signal issue was found and corrected, DVR recording and playback issues stopped. Were the techs that told you the issue was due to the cable box and/or told you Contour 2 would solve your issue contract techs? Have you ever had an in-house Cox tech check your signal strength at the tap? If you know the neighbor that shares your tap, ask them if they've had any cable issues. Even if the neighbor says no, your issue could still be caused by a faulty port at the tap.
Cox techs (ones with Cox business cards and driving Cox vans) have been out about 6 or so times, all have confirmed the signal is good at the DVR, at the cable modem, at the splitter, at the feed into our home, and at the junction box. Again, the most recent failure was a recording that played back once without issue (therefore not a signal issue), about 2 or 3 hours after the recording was completed. Then attempting to play that recording again about 6 hours later failed with error code 188.8.131.52. Another attempt to play that same recording about 12 hours later could play the recording, but it froze at about 2 1/2 hours into a 3 1/2 hour recording. This has happened in the past, with this and prior DVRs, although rare. Usually error code 184.108.40.206 occurs on the first attempt to playback, and never self-recovers. The failure is apparently due to recordings somehow getting corrupted, sometimes hours or days later on what was once an uncorrupted recording.
and yes, it was during visits from Cox techs in the last year or so that advised me that switching to Contour 2 Cisco box would probably solve the problem. I was also told of a software update back in November, 2020 (or was it 2019) to solve a problem with the Cisco box, but it didn't fix the problems I'm having.
I don't know if any of our immediate neighbors have a DVR.
In some cases after getting an error code 220.127.116.11, after power cycling, I was able to play back a recording, sometimes without issue, sometimes with a skip to end, the most recent a 3 1/2 hour recording that froze up at 2 1/2 hours, that was watched once without issue, then got an error code 18.104.22.168, then the next day it would play but freeze up at 2 1/2 hours. This has been pretty much the pattern with all of the Contour 1 Cisco DVRs we've had.