RKB50 Slow WiFi Speeds

Yet another Orbi WiFi  speed Post. When on Comcast I was clearing on my iPhone XR anywhere in the house 250+MB down and 10-20MB up. 

Now that I have Centurylink Fiber I expected better. I was sadly mistaken. I've done over 20 speed tests while changing settings left and right and Average is 150MB down and anywhere from 30-389MB Up (sitting right next to it I might add). 

Now hardlined to the RBR50 I am getting decent speeds, ~300MB on average. I cannot for the life of me understand how my WiFi got worse with a better connection. Any suggestions that I havent tried would be greatly appreciated. 

I've already had CL tech out here and testing direct from the C424G We get almost a GIG everytime. WiFi on it was okay (250MB) when near it. 

I've read most of the posts and I can give you a breakdown of everything I have done.

1. I moved from a Comcast 500MB COAX connection to a CentruryLink 1G Fiber connection.

2. CL provided a Adtran C424G Modem/Router Combo unit. 

3. I have disabled all the radios on the CenturyLink Modem, placed the RBR50 on the DMZ list. (I did try Transparent Bridge mode and this didn't make a difference, yes I enabled vlan tagging 201). 

4. I have tried placing the router in AP mode, (which disabled Circle, kids were happy).

5. I disabled 20/40MHz Coexistance, Daisy Chain and Netgear Armor. Enabled MU-MIMO, Beam Forcing. 

6. Disabled the Guest Network on the Orbi

7.  I used a WiFi analyzer and set the 2.4G network to channel 8 and 5G to channel 48 as these were the only channels not in use.

8. Finally I did a factory reset and started setup from scratch. 

9. I have a total of 28 devices ( mostly smart home ) connected between the RBR and the RBS.