John,
After doing quite a bit of troubleshooting I decided that the wired Ethernet controller was one of the suspects, so I unplugged the ribbon cable and switched to WiFi. Long term I don’t like this solution because it relies on a powerline extender in my garage, but I have been on WiFi for the last 2 days, and sure enough, it has yet to lock up like it had been quite frequently with the hard wired ethernet connection. I’m not 100% confident that the problem is completely gone (I’ll need more time for that), but it sure is looking like the issue may be caused by the ethernet module. My understanding is that the ethernet module uses a chipset that relies on a software based TCP/IP stack. I’m wondering if the built-in WiFi module has hardware based TCP/IP handling?
Yesterday while I was browsing some of the old forum posts I saw that some other people had been reporting lockups similar to what I was seeing, so I don’t think this is a new problem. At least one of the other reported lockup problems seemed to have started after a couple of years of reliable hardwired operation. That mirrors my situation. That person reported that setting up a VLAN with only the OS controller on it solved his problem, so that suggests that some other newly deployed equipment on the network may be sending some type of broadcast message that the software-based TCP/IP code chokes on. My equipment will support a VLAN, but I will have to rewire some things before I can make that change because I have a separate switch downstream from the switch that has the VLAN support.
Due to the random lockups I’ve been experiencing, I have been reluctant to enable my automatic programs. It’s interesting that you don’t seem to see the lockups unless you’re using manual watering. I think I’m going to continue with manual watering for now until I gain a better confidence that the WiFi interface isn’t susceptible to the lockup problem. I have noticed that sometimes it takes *much* longer than it should to connect to the controller from my iOS app, but I don’t know if this is related to WiFi connectivity issues or something else. At least it hasn’t locked up the controller yet!
I haven’t tried Ray’s above suggestions yet, but the only item in my setup he mentions that relies on DNS is the weather server. I would need to switch back to the hardwired connection to validate his suggestion, so for now I’m going to continue with WiFI to ensure that it isn’t susceptible to the bug in the first place.