Internet Speeds

Recently setup pfsense on a protectli vault. I have a fiber connection running through an ONT that i directly connect to my appliance. I run my 2 PC’s through an unmanaged switch that’s connected to the appliance. My speeds are exactly how they should be with 500/500 on the two PC’s. However, When I connect my old netgear router that I have put into access point mode into the switch, the internet speed for all devices drops to 90/90 or lower and I start having issues connecting to games and other applications. Went and bought all new cat6 cables incase this was the issue and the issue still occurs. Any suggestions on what might be causing the issue once I add the router(converted to access point) to my network? If i unplug the router from the switch all other devices hardwired are running normally.