Orbi RB50 performance is slow

I have the Orbi RB50 with 1 satelite. Every once in a while, my peformacne gets extremely slow. I have Fios 1G service. When Orbi is running correctly i get 500+ down/upload speeds. When it gets boggy, it is consistently 80-90. I have this bridged with the Fios Gateway they gave me. This is in the basement. It is hardwired from the basement to my upstairs into the back of my main Orbi. I can log into my Fios router and check the speeds and they are fine on that. So something is happening with the Orbi. I've done resets, the firmware is up to date. I've even changed my wiring come from the wall to the Orbi. Nothing seems to get the results to instantly change back. All my settings are fine. Changing all of the settings I have read on the internet does nothing. The other Fios Router's wifi has been disabled. I had this happen about 1-2 months ago. It was like this for about 5-6 days. I thought maybe it was an ethernet cord so i changed it and that seemed to make the difference. But its back at it again. I'm pretty sure the cord is fine. When i put the system in (its been active for about 4-5 months now) it was running fine. So the wires cant be faulty that the builder put in otherwise they wouldnt have worked in the first place. Something has to be going on with the Orbi. Any thoughts? Thanks.