Remotely configure Sophos SG 135w over the Internet (Webadmin)

Hi everyone. I am new to dealing with these appliances and I need my boss (who is in another country) to remotely configure the device. So, at the moment he has to be connecting to my laptop using TeamViewer or AnyDesk in order to access Webadmin through my laptop. Is there a way for him to access Webadmin and configure the device without connecting through my pc. What I did was connect an ethernet cable from a router LAN port to the WAN port (eth1/WAN) of the sophos. Also, a cable connecting my laptop's Lan port to the Lan port (eth0/LAN) on the sophos. The device is on UTM 9.6 firmware.