Unable to access gre tunnel from Wifi Zone

On my cyberoam device I have 2 subnets on different zones as follows:

LAN - 192.168.0.0/24 - PortA

LAN2 - 172.16.16.0/24 - PortJ

I also have a gre tunnel configured on port C linking to our corporate HQ.

This setup works perfectly on Cyberoam.

I have just migrated the entire setup to Sophos XG.

The users on LAN2 are unable to access resources over the GRE Tunnel.

Everything else seems to work perfectly.

Please what could be the issue?