Hi, thanks for taking a look. I tried switching the Hub back to router mode, unplugged my local router, and plugged in a laptop with a wired connection (so the laptop was the only cat 5 connection into the Hub). I reran the speed test, and it is still quite slow (around 137 down and 10 up). I also tried running the speed test over a wired connection directly into my local router (with the Hub in Modem mode), and that was about the same performance.
I think this seems to strongly indicate that the problem is not within my power to resolve. I am happy to run additional tests if there is anything else that makes sense to try.