Windows 11 ethernet speed issue (slower in one direction)

[MOoD90s 0]

I recently upgraded my LAN from gigabit to 2.5 gig, replacing a unmanaged gigabit switch between my Windows PC (HP Spectre X360 laptop running Win 11 Pro) and my NAS (Unraid) with a 2.5 gig version and adding a 2.5 gig ethernet adapter to the NAS. My PC already had a 2.5 gig adapter (in a Thunderbolt dock). After installing everything, I've found that the connection between the PC and the NAS is slower in one direction.

Using iperf, with the NAS sending a stream to my PC, I'm getting ~1.5 gigs; in the opposite direction it's full speed, about 2.35 gigs. At first I was getting barely a gig, but I rolled back to an older driver, did a Windows network reset, and played with some settings in the adapter properties (turned of all the offloading, packet priority, and VLAN) and that got it up to 1.5. The connection is stable, it's just not getting full speeds both ways.

I know it's a software/configuration issue and not a hardware problem because I've tried:

• booting the same PC to a Linux live USB and it gets over 2 gigs in both directions
• using another laptop running Windows 10 on the same Thunderbolt dock and it gets over 2 gigs both ways as well

It's connecting through an HP Thunderbolt Dock G4 with an Intel I225-LMvP ethernet controller. The driver version is 1.1.4.43, which is the latest driver that HP supplies specific to this dock. More recent drivers directly from Intel work but are slower.

Any ideas of how to troubleshoot this further?