Hello everyone,
We are using a Sophos XG as main router. Currently we are migrating from one network to separate networks for clients and server. We use tagged vlans from router to switches and untagged vlans at the switches for the clients. All networks are using our sophos xg as default gateway. We configured vlan interfaces on the xg for every network. For the two vlan networks, we also configured DHCP Relay agents on the xg. All DHCP Relay Agents point at the same Windows 2016 DHCP Server.
The server reside in the standard untagged vlan. Those are all windows ad members so we want them to use our windows DHCP Server. The Server is located in network A and the clients in network B. Our IT department has its own vlan and network, lets call it network C. When a new client is connected to one of the networks DHCP is working as it should, at all 3 networks.
Network A does not have a dhcp relay agent and uses a separate dhcp server.
But when i move a clients from network b to c or vise versa, clients receive their "old" ip address from the dhcp server and cant communicate. First i thought this might be a problem with dhcp leases, but after asking this question at the microsoft community a guy pointed me at the fact that a dhcp client uses a state called init-reboot. A client trys to get its old ip address from dhcp before requesting a new one. He told me to take a closer lock at the dhcp relay agent... but there are no further configuration options, just the basic fields.
We had the same thing with two red devices that are using a dhcp relay as well.
Did anyone had a similar problem or has any suggestion what to do?
Greetings
Freddy
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