PXE boot very slow when connected to opnsense router

[turbocharcgedentity]

I have a windows 7 pc running a program called IShareDisk, which is basically a pxe server/manager. It is connected to a hub which is then connected to a bunch of other pcs that rely on the pxe server to boot. When I connect the LAN port (1gbps) of the opnsense directly to the wan port of hub, all the pcs that boot on PXE start to move at very, very slow speeds. I then connect the LAN port of the opnsense to my tp link load balancer WAN, then connect the LAN port of the tp link load balancer to the hub, then all the pcs start to boot normally. Is there a setting I need to change or does opnsense don't support this type of setup?