What the app does is update the IP address in Homey of the device once it receives a status update for that device (matching is done on device id) and the currently registered IP address does not match the IP address of the received message.
So either the IP address in the Shelly app is incorrect (not synced because cloud is disabled), or there is indeed something wrong with your network where the device is reporting a different IP address in it’s CoAP message or you manually switched the IP address of two or more devices in Homey while the mechanism is changing it back based on the original device id which was saved during pairing. You could try rebooting the plugs or worst case scenario, just remove and re-pair them.
