Can't access PBS/PVE from behind a fortinet router

[approximater]

I have a PBS in the home office that is behind a NATing modem which I have configured to forward port 8007 to the PBS internal IP. I can access the PBS web portal fine from my mobile using 5g and from another house which is also behind a modem doing nat but when I try from an office that has a fortinet router it times out. The strange thing is it has a firewall rule allowing and NATing all outbound traffic from inside and I can access any other public site from that office just not my PBS server. Has anyone else encountered this? I assume it's more of a fortinet issue than a proxmox one but trying to get useful support from their forum is like trying to squeeze water from a stone.