I've done a search on this and have not had much luck to match my issue. Have a AC86U running Merlin 386.1 and my SmartThings hub is constantly being kicked off the network. Looking at the system log I see a bunch of "not mesh client, can't update it's ip" for the MAC address of the hub. It does this to other devices sporadically however it seems to really have a problem with my SmartThings hub. As stated I have done a search and tried a few things that were mentioned such as changing WiFi channels from auto to a set channel, picking ones that have minimal interference from neighboring networks.