I'm no network expert either, but if the appliance is 2.4ghz only, and the network is dual band configured with shared SSIDs as is common, then I believe the issue is often to do with band steering, which tries to force wifi devices to connect using the higher frequency bands by kicking them off if they try to connect using the 2.4ghz band.
Usually, if using shared SSIDs, temporarily disabling 5ghz, allows the appliance to find and connect to the network, and once the wifi connection settings are configured on the device you can turn 5ghz back on, on the router / AP and in future it will detect that the appliance can't do 5ghz, and not kick it off.
If you have this issue and you have a stupid router that doesn't let you disable 5ghz (typically an ISP supplied router with semi locked down settings) then a work around that's worked for me is to temporarily set up your phone as a 2.4ghz wifi access point using the same ssid and wifi password as the router, turn the router off and set up the connection using that.
If may help to reboot the router after turning 5ghz off, but shouldn't make a difference. If that doesn't work try temporarily disabling mobile data on your phone to force it to use wifi, and connecting on the same network, in case it is a routing problem.