RBR50 and slow internet

I have an Orbi RBR50 router with two satellites in my house as its about 5000 sq ft and we have devices in each room. The distance between the router and satellites is at least 30 ft. I also have centurylink fiber as I am paying for gigabit service. The current software according to the Orbi app is 2.5.1.8. Only the Router is hardwired as I have an older house. The setup is R-S-S if you look at it. 

Currently the setup is ONT->C3000z->Orbi RBR50 as a router.

I turned off the wireless capability of the C3000z modem so that the only router that my products see is the Orbi.

When I plug in a desktop directly to the C3000z modem given by Centurylink, I get about 940mbps to 980 mbps download speed. However, when I test the speed from the Orbi app which is connected directly to the modem, I get an average of 550 mbps (Orbi is connected with a Cat7 cable). Shouldn't it be reading close to 1,000 mbps?

On wireless however, I only get about 80-130 mbps through the mesh system throughout the house which I feel is very low, even when I am standing next to the router. I test through google's speed test and speedtest.net on both my iPhone XS Max as well as my HP laptop. 

I have already factory reset the router last week because sometimes the Orbi router was reaching speeds as low as 40mbps and then restarting it every other day would bring the speed back up to 115 mbps. But factory resetting the Orbi did not increase my speed past 130mbps. I have also tried putting the Orbi as an access point but maybe I didn't do it correctly? I did not set up the PPPoE or anything. All I did was turn on (and tried turning off) the C3000z wireless network and then went in the Orbi settings and put it in AP mode. But that did not do anything. Are the SSIDs from the modem and the Orbi supposed to have the same names maybe? Another thing I noticed is even when I turn the C3000z wireless 5g network on and connect to that with my phone when I am next to that modem/router, I only get 170 mbps speed (so a small increase when compared to the Orbi).

The settings I have within the Orbi app are changing the 5G channel to 48 (which isn't used as much in my neighborhood), enabled WMM, enabled 20/40 MHz coexistence, Daisy-Chain is disabled, enabled Beamforming, enabled MU-MIMO, and fast roaming is disabled. 

I was thinking about calling up Centurylink and getting the PPPoE password so that I can setup the DMZ and cofnigure the Orbi's for bridge mode and VLAN tag 201. But I am not sure if this will do anything. Am I doing something wrong? When I first set these Orbi's up (bought from Costco 5/28/18 so I cannot return past 5/28/20), I was getting speeds of up to 220 mbps which is why I returned the Google Wifi routers. But I am not sure what has changed since then because I only started messing around with the settings once the speed dropped significantly.