I'm setting up a WDS (Windows Deployment Service), the WDS server is in a different subnet than the clients that need PXE.
These subnets are connected through a VPN tunnel. Routers are pfsense.
But on the clients' router, I don't know what settings I'm going to put for PXE to work.
I've tried going to several forums, tried several different settings and none of them seem to work.

Below are images of the current state of the network and its settings.

image1 image2 image3

  • WDS does more complex things than this, broadcasts and replies on UDP ort 4011 is one of them, that is hard to route, also TFTP on UDP 69 is not great over routed networks (any fragmentation kills it) WDS more or less needs to run locally, but there is lots of different PXE implementations that can run in your network, iPXE can work mostly over http instead, you just need a local TFTP server for initial boot loader file(s).
    – NiKiZe
    Nov 8, 2021 at 12:58
  • @NiKiZe, PXE works across subnetworks if you enable the corresponding IP Helpers. TFTP does not have issues with subnetworks, and routers do not fragment traffic.
    – Pat
    Nov 9, 2021 at 20:43
  • @Pat, there is no guarantee that they don't, and over a wan they are not unlikely to fragment (different MTUs and it has to), so I still stand by that TFTP "is not great on routed networks"
    – NiKiZe
    Nov 10, 2021 at 2:06
  • @NiKiZe, TFTP with max packet size = 1468 => MTU=1500 => No fragmentation. TFTP is the PXE protocol used by MS WDS/MDT/SCCM and they cross router boundaries w/o problem. TFTP has issues with high latency links (i.e. Satellite links) if the latency is low and you use RFC 7440 you have no issues.
    – Pat
    Nov 18, 2021 at 23:24
  • @Pat, are you claiming that MTU can never be less than 1468?, Are you also claiming that packets can't come out of order?
    – NiKiZe
    Nov 19, 2021 at 1:26


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