Very slow upload speeds on Windows 11 (Apple silicon)

Hello,

For the past couple of days, I've been testing Parallels Desktop (trial version) to check if it is a good alternative to other hypervisors. However, I've stumbled upon a network issue that I can't find a fix for.

I've checked other threads (e.g. https://forum.parallels.com/threads/slow-upload-speed-on-win11.355998/ ), but so far I could not find the correct solution.

These are the current specs:
MacBook Pro 16-inch M3 Max 36GB RAM
OS: Sonoma 14.2 (23C64)

Parallels Pro Edition 26.2.2 (57373)
Windows 11 ARM64

The symptoms:
Currently, when I try to use the host (OSX), I can get around 80Mbits download and 30 upload. If I repeat the same test using the Windows 11 VM, I get around 63Mbits download and 3.5Mbits upload. While the Download is more than enough for me to work, the upload is too low.

I tried every solution I could find:
- Tried changing between Bridged and Shared Network, but it didn't work.
- Tried to change the Offload.Tx.LSO. It was already set to "Disabled", but I also tried the IPv4 and Maximum modes, but there was no change in performance.
- Tried to enable and disable the Ethernet adapter. I disabled it via Device Manager and also via the Network & Internet menu. Nothing changed.
- Tried to change the configuration profile for this VM in Parallels, and set it to Gaming, Productivity, and Development. Got the same results.


Maybe I need to execute them in a specific order, maybe this is just another bug. IS there anyone who can shed some light on this?


Performance-wise, everything else seems to be working just fine and I have no complaints, but if I can't fix the network performance then I'll have to give up on parallels.