I don’t have this particular router to test so unfortunately I can’t diagnose the issue. The library used in firmware 2.1.9 is UIPEthernet, which is a pretty popular library and should be compatible with most routers. One thing you may try is to set a static IP (we recommend doing so on the router, using DHCP reservation, but you can also try it on the OpenSprinkler controller, by settings the static IP, gateway (i.e. router) IP, subnet mask, DNS IP correctly. Not sure if this makes any difference.