Another Pace 5268AC + Orbi RBK50 issue....

So, here's the deal. I've setup an Orbi (latest FW, 2.5.1.8) in router mode (AP made no difference) behind a Pace 5268 (wifi off). Tried multiple configurations and my wifi speed is blah. I had it up to around 400 at one point, however, by the next day it was back to 200-250 (same as the speeds I was receiving from the 5268). After another couple of days it was struggling to reach 200. I have gigabit through ATT and the 5268 shows 999 download on the internal speed test. The only thing I have to test the hardwire gigabit speed is an Xbox One X. It usually pulls between 700-900. Directly connected to the 5268.

I've put the Orbi in DMZ+ mode, tried opening all TCP/UDP and tried in AP mode. No matter what I do the speed stays the same. The satellite has issues connecting in AP mode but seems fine in router. 

I've read virtually every thread I can find on this issue but haven't found any solutions that work. Is there any way to get a consistent 400 (wifi) out of the Orbi while using the 5268? I know I'm not going to see much over 500, I just want something better and more reliable than what I was getting out of the 5268. Any ideas? The Orbi was a refurb from Newegg. I'm running out of time to return it... and ideas to make it work... Thanks in advance..