First, just to double check: are all the units on the same network or different networks? From your description, it sounds like they are in different networks. In any case, because the MAC address on OpenSprinkler is software defined, if you put multiple units on the same network, make sure you change the ‘Device ID’ option to give each device a unique MAC address. Otherwise you will get IP conflicts issues.
It is the same network and we statically assigned the IP addresses to the units. They are on different switches in our network, but I guess having the same MAC address is causing an issue to those devices. Is the Device ID hex? We are looking at having nearly 55 units in our network – if everything goes well. Do you for see us running out of Device IDs?
Next, regarding the Jumbo Frames, I am not aware of any issue of the EtherCard library (which OpenSprinkler firmware uses) when Jumbo Frames are enabled. From your description, it seems there is strong evidence that there is indeed such an issue. I have to do some research on this. In the meantime, is it possible to disable Jumbo Frames on the three PowerConnect 2808’s and see if this resolves the issue?
Changed the Device ID on one of the devices that was having issues. Seems to have resolved the odd behavior as the other two went down already. Jumbo frames was still enabled on the switch.