@DaveC: this is the first time I heard about the DHCP burst issue. I suspect it’s an issue with the EtherCard library that OpenSprinkler firmware is built on. I will use WireShark to monitor the web traffic and see if I can reproduce the issue.
Before we proceed, which firmware do you have? If you don’t have the latest firmware 2.1.4, I suggest that you upgrade to firmware 2.1.4 because it contains several Ethernet related bug fixes that may have fixed the issue. Even if your controller already shows firmware 2.1.4. I still recommend you to re-flash, because there was a silent update to 2.1.4 firmware a couple of weeks ago that wasn’t announced. In retrospect we should have numbered it 2.1.5 but the changes were too small to make it 2.1.5. Make sure you click on ‘Download Firmware’ before updating, so you can grab the latest files.
To be more specific, these are the most recent changes:
https://github.com/OpenSprinkler/OpenSprinklerGen2/commit/3f32a564e278f32ebfd3aae7efa15769f10e83f2
there is a bug with the way timeout is calculated and in some cases that could cause the controller to get stuck in the ‘Connecting…’ loop for a while. I should have brought this up earlier, but I am not 100% optimistic that this completely solves the issue. So I suggest updating the firmware and let me know if the issue still persists.