Hi,
Could you please try enabling 'persistent keep alive' in Wireguard settings? Services -> VPN -> Wireguard -> Edit your instance -> Edit peer -> Advanced settings -> Persistent keel alive : 20.
Let me know if this helps.
Also, does the device reboot helps to reconnect? You could try configuring auto reboot in Services -> Auto Reboot -> Ping/Wget Reboot to ping your WG peer, and in case of failure, reboot.
Kind Regards,
Andzej