Please use one phone for the Gate app and one phone as a hotspot. Start with enabling the mobile hotspot on the second phone. On iOS, this is in Settings > Mobile Hotspot. Make note of the password and network name (usually Name's iPhone). On Android, go to Settings > Connections > Mobile Hotspot and Tethering.
Then on the first phone, open the Gate app and start the connection process (Settings tab > Change WiFi Network) and when it prompts you for your Home WiFi network, select the iPhone. Enter the password as seen in the Mobile Hotspot menu of the other phone.
Once connected, keep the hotspot enabled. The lock will update firmware. Once it is to version 18.104.22.168, it is good to reconnect to the original network. To check on the firmware version, go to Settings > About this Gate > Versions section > Firmware.