RBK 753 Download 1/2 of Upload Speed on Satellite

Just picked up the RBK753.  I live in an apartment with google fiber.  The fiber jack is at one end of the apartment, while my office is at the other.  I'm looking to use mesh as a way to get ethernet internet into the office without leaving cables strewn across the floors (there's nowhere to tuck them, and I can't go making drops). So essentially I'm relying on the backhaul for connectivity.

One Router, one Satellite (not using the second satellite). They are approximate 30ft apart with a wall between them. Both are running firmware 3.2.16.6

• If I connect my PC to the router via ethernet (super long cable), I'm getting 900/900 as expected.
• If I connect my PC to the satellite via ethernet, I'm getting 350/850
• Same desktop, same network card, same cable in both test scenarios, cable with the two different results based on whether I connect to the router vs. the satellite.

I would expect some speedloss given that I'm relying on wireless to get from one spot to the other, but I would have expected that speedloss to affect the download and upload roughly the same.  I would never expect a difference of over 50% like this.

I have already tried rebooting both router and satellite, as well as doing factory resets on both, but results did not change.

Any thoughts on what might be going on here?  Thanks in advance!