How to create a gigabit local network that's connected to fast Ethernet router ?

So basically I have 2 pc's with gigabit Ethernet ports but my local network is only 100 Mbps. my actual internet speed is 10 Mbps . the router I'm using is a TP -link TL-WR845N which has 100mbps Ethernet ports instead of gigabit ports. When I try to use OBS NDI plugin to stream over the network OBS alone uses up 100 Mbps network so I'm bottlenecked by the router. I don't need a gigabit router but I need gigabit speeds over the local network among the 2 pc's. How do I do it? will a network switch with gigabit ports help. I don't really need the wireless router I have. I just need a gigabit local network that's connected to the interned at megabit speeds