HELP No IP Address for Sonoff Devices

My Sonoff devices keep loosing connection to the Smartthings app. The devices are online as shown in the above pic, and I can control them by entereing the ip address directly through a browser, but smartthings has lost the IP address. Eventually they will come back online, but I cant seem to figure out why.

I have some of the devices assigned static IP’s in my router, but it doesn’t make any difference.