I wasn’t aware of postinit scripts :(. Looking at postinit now, it seems that it would need network mount to work through default router (the firewall) and we tried to minimize what we are enabling through the firewall. XenServer PXE boot (testing host) doesn’t support classless static routes either so we had to let TFTP through to make this work.
Maybe we could reconfigure our “single fog server - multiple subnets/vlans” setup? We have tried to create multiple network adapters on the same FOG server and to have clients from each network to communicate with the server through IP address in the same subnet but we were not able to set up this to work and I’m not sure if FOG supports this as I have seen that FOG requires network interface to be specified in some places.