Can you provide some more details, like:
– does the controller respond to button presses?
– is the time displayed on the LCD correct?
– does it respond to ping?
Just seeing ‘network error’ does not necessarily mean it has lost response — the UI has a default timeout (3 seconds or something like that), if it doesn’t get response within 3 seconds, it will display network error. But it could be that it took 5 seconds for the response to come back. For that reason, it may be better for you to use the follow API test script:
http://raysfiles.com/os/TestOSAPI.html
which does not rely on the UI, and it just pulls data directly from the controller. If you get a response, that means the controller is working fine.
Also, just to double check the firmware is flashed correctly, go to About page and see if it shows 2.1.9(5). Or, if you use use the TestOSAPi script, check the /ja result and look for a variable named “fwm” see if it’s value is 5.
One last thing you can try is: if you haven’t done so, try set a static IP on OpenSprinkler: go to Edit Options -> Advanced -> turn off Use DHCP, it will auto populate the fields with your currently assigned IP and DNS, gateway etc, so you can just submit changes (or make edits if anything looks incorrect). Then do a reboot of the controller. This way it will disable DHCP and won’t send DHCP requests (which also keeps UDP broadcast disabled).