John,
The forum posts I saw were related to the controller crashing, and I’m not sure if that’s what you’re seeing happen when a valve gets stuck open on yours. When it happens to me, my controller is truly crashed and will not recover without a power cycling. The buttons on my controller become unresponsive, and the clock stops updating. I believe what I’m seeing is what the other forum member was seeing when they posted about the VLAN solution a couple of years ago. In their case, isolating the OS controller onto its own VLAN completely solved the crashing problem.
Have you ever seen a situation where the log files in the controller show incorrect runtimes for zones? I’ve actually seen “impossible” run times in my log files (I.e. a zone is reported to have run longer than it possibly could have based on the surrounding zone start and run times). This is one of those symptoms that leads me to believe there’s data corruption responsible for the controller crashing. Since you’ve noted that you have zones that run longer than they should but then finally shut down, I’m curious if your log files reflect that actual run time.
You noted that you leave the app running in the background on your iPhone. What happens if you actually close the app after you start a manual zone? In my case, I’ve seen the controller crash even when there’s no iOS app running (and I don’t necessarily even have to be running a zone for the controller to crash). Based on my symptoms matching what the other forum member posted quite some time ago, I suspect a VLAN would solve my problem, but your issue sounds a little different. I’m currently running an ASUS router with several smart switches. I plan to switch to a UniFi system, but I’m waiting for them to release more of their WiFi 6 hardware before I take the plunge. I really like the UniFi system and the configurability / troubleshooting that you get with it.