Perhaps I have a unique hardware issue with my Mio+. But it is clear the clock issue continues after all. As I've been sitting here for the past 30 minutes, the clock has deviated dramatically 2 times. It is now 3 hours in the future and probably the date is in the last century (1969 or 1970). I would have to power it up to check that.I downloaded from online and installed the August 13 TNAP 4.1 image. All images loaded prior to this did not solve my clock issue when I switched my Mio+ to standby. My Mio+ clock has always been accurate if I left the receiver powered. However, this latest release may be the magic bullet. So far, the clock is remaining correct even in standby. I will continue leaving the receiver in standby whenever I am not using it to test if it remains accurate.
Added: This morning I installed the new August 15 image. Continuing to monitor.
For the record:
1) I have carefully followed the updates for TNAP 4.1. The current time shows Friday, January 2, 1970 11:16 am. Time is approximately 3 hours in the future and the date is 51 years behind. My current software is TNAP 4.1 2021-08-15.
2) I have never used anything but the Internet time synchronization method. I have never used transponder time sync since owning this receiver. I learned years ago with previous receivers that transponder sync doesn't work in Canada. My Internet is stable and reliable.
3) When needed, lately if I reboot, I am using the deep standby selection. It seemed in past, this provided a better reboot since it powers down the receiver completely. When powering up, the receiver goes to clock mode. I then press POWER on my remote to switch on the receiver.
4) If I only do a restart, then the receiver restarts but the TV does not display anything. I must cycle the power on the receiver so the TV then syncs and displays a picture.
5) My workaround is OK for me. I simply never power down the receiver to standby. Doing this keeps the receiver totally accurate. Some don't like to leave the receiver on all the time. I don't mind.
6) It seemed when I first installed this software update that it had resolved the issue since I could leave the receiver in standby for long periods (even overnight) and the clock remained accurate. It almost seemed like the issue developed again over time. As I'm using the receiver, it has just corrected itself automatically. It will remain accurate now as long as I don't go to standby.
7) Months ago, we had a very bad lightning storm. One particular strike nearby caused a power hit. This seemed to have an impact on receiver operation. I changed HDMI cable, etc. This is why I'm wondering if I have a hardware issue.