New ISP Spectrum. Internet speed is halved using router.

Modem: Arris Surfboard 6183

Router: NetGear R6400V2 (V1.0.4.84_10.0.58)

QOS, Traffic Meter, SmartConnect disabled.

Recently just moved and bought the Spectrum 400Mbits plan. After hooking up my router, my speed tests always range from 170~230Mbits. All the PCs (wired) and Phones get that speed. Decided to do a straight wire to my PC and was getting the 400Mbits range. Tried different ethernet cables from Modem to Router, issue persists. Tried a hard reset on router. Speeds are basically halved.

Is there a solution to fixing this issue? Could not find any. Thank you.