For a RUTX11 in a similar configuration, from /etc/config/network:
config interface 'wglg'
option proto 'wireguard'
option private_key '(hidden)'
option public_key '(hidden)'
option listen_port '51820'
list addresses '172.31.253.2'
option disabled '0'
config wireguard_wglg 'lsrapt'
option public_key '(hidden)'
list allowed_ips '172.31.253.0/24'
list allowed_ips '192.168.0.0/24'
list allowed_ips '192.168.1.0/24'
list allowed_ips '192.168.9.0/24'
list allowed_ips '192.168.159.0/24'
list allowed_ips '192.168.176.0/24'
list allowed_ips '192.168.100.1/32'
option description 'lsrapt'
option preshared_key '(hidden)'
option route_allowed_ips '1'
option endpoint_host '(hidden)'
option endpoint_port '51820'
option persistent_keepalive '60'
The wireguard interface at the other end is at 172.31.253.1/24. Packets to addresses in allowed_ips are routed through the wglg interface.
To route all traffic, you'll have to set "list allowed_ips '0.0.0.0/0' instead.
Regards,