Hello,
Perhaps you are using the WiFi as a WAN source? It could be the case that your WiFi device loses the internet connection for a few seconds and disconnects from the WiFi. I was able to scan the WiFi networks on the RUTX50 running the latest firmware and was not disconnected from the network.
Maybe you could test if the behaviour reappears when using a different device to connect to the RUTX50?
Best regards,
DaumantasG