If you wish to use a dhcp relay or ip helper-address always place those commands on a L2 switch that supports those features, not on the router.

vpnrouter wrote

If you wish to use a dhcp relay or ip helper-address always place those commands on a L2 switch that supports those features, not on the router.

I'd like further comment on this issue, as I am having this problem with this router, and I found this TechNet article https://technet.microsoft.com/en-us/library/Cc779610(v=WS.10).aspx which says that routers can / do have dhcp relay capability. At any rate, I also have a TL-SG2424 managed L2 switch and cannot find a DHCP relay option on it either.

Any ideas?