Has anyone else seen something similar?
I had an RB1200 in this location. My upstream changed from port 2 to port 3. My downstream stayed on port 1. Downstream traffic through the device was horrible, limited to single digit megs. Upstream traffic through the device was fine, limited by wireless conditions (about 60 megs). I could do simultaneous TCP BTests, one from an upstream router to this router and one from this router to a downstream router. Both tests ran simultaneously would use the full capacity of the pipe available (90 megs from the upstream and 60 megs to the downstream). The wireless conditions were obviously adequate as simultaneous TCP tests maximized throughput. The difference being these tests were ran to\from the device instead of through the device. Let's try moving the cable and IP addresses to port 2. Everything works fine.
I was on 5.26. I upgraded to 6.19 and then 6.23, making sure to upgrade the firmware each time. No improvement. Let's move the cable and IPs back to port 2. Everything works fine.
Okay, I port 3 must be bad, let's swap this out with a new RB1100AHx2 that I have so that I don't have any future port failures. The new RB1100AHx2 does the same thing in the same situation.