The reason that TMG1 is there is precisely to isolate your lab machines from your "real" network, so that (among other things) they can have any addresses required by the lab, such as static addresses for lab servers. Another good reason why they
shouldn't see the real network is that normally in a class environment you will have several replicas of the same machines (one for each student), and they would conflict with each other (due to having the same names) if they had an address on the same network.
So you really should not be letting any external addresses be assigned to them via DHCP, regardless of whether the network is wired or WiFi.
That said, if you only have one copy of the lab machines (for instance if you are an MCT training yourself rather than setting up a classroom) then most labs (but not all of them) will work correctly if you remove the TMG1. You then configure the virtual
adapters for all lab machines so that they connect to the External virtual switch instead of the Internal one. Change the network properties on the virtual Ethernet adapter on each machine so that it uses DHCP, and it should work for
most labs. It has the advantage that you are now running one less machine (the TMG server) which can help performance if you are running the VMs in a memory-constrained host.
