XB6 Modem limiting network switch to 100mbps

I have the 600mbps plan with the XB6 modem. Since the XB6 only has two ethernet ports and I have numerous devices that need an ethernet connection across the house, I have a 100ft CAT6 cable that goes from the modem to another room into a network switch. The switch is gigabit, and Windows devices connected to the switch show that LAN is working at gigabit, but running internet speed tests show that devices connected to the switch are only getting 95mbps. Going into the modem settings in Gateway>Hardware>LAN shows that the modem is limiting that port to 100mbps. When I swap ports, it limits the other port to 100mbps only as well. I know its not the cables, because when I plug devices directly into the modem with those same cables, I get the speeds that I'm supposed to for my plan. So it seems like the XB6 just doesn't like the switch for whatever reason. Is anyone having a similar problem? Does anyone have a solution? Thanks! If it helps, the switch is TP-Link 5 Port Gigabit Ethernet Network Switch (TL-SG105)