First of all, make sure you're exposing 2.4GHz WiFi frequency for your robots, as that's what they're using! But additionally, it seems like whatever network card these devices are using, is pretty aggressive in entering power-saving mode - and it just drops off the network. If the robots are on the fringe of your network, opening the app and trying to update the status of your robot might not work - Landroid Cloud pinging your robot simply doesn't get through. However, it seems like having a device constantly maintaining the connection to the robots will counter this issue. For me, that device would be Home Assistant, but you'd probably be fine just having the Landroid app in a smartphone without battery-saving features enabled.