cm1200 & XR500 half wifi speeds

So just moved to a new house, and I also got a new modem, a CM1200 for gigbit speeds. 

ISP is 1200mbps, and I was troubleshooting with them, but they said they are sending those speeds, so they think its a modem/router issue. 

Ive HAD my XR500 for about two years, and never had gig speeds, always paid for 300-400 range, and always was able to get those speeds wired and wifi. 

Now that I have 1200, i get about 5-600 speeds on 5g on my iphone and devices, basically half of what im paying for, i tried a direct connection, and was even slower. 

Weird part is, when I do the setup on my XR500 (I did a Factory reset) it clocked 980gbps. Soooo really strange why im not getting faster speeds than 600.

I did a reset so everything is defauly settings, on firmware V2.3.2.66

any ideas?

If the router is seeing 980, but not pushing anything lose to that? Is there something going on with my signal?

BTW is there any settings or updates i need for the CM1200?

thanks!