Excessive NAKs after upgrade from Windows 10 version 1903 to Windows 10 version 21H2/22H2

[Robert Bui]

Hello all,

After we've upgrade our computers from Windows 10 version 1903 to version 21H2, we are getting excessive NAKs, when transfer >100GB data file across Gigabit local network.

On 1903, we may receive on average 200-400 NAKs per failed section. We may get a failed section every 100-200 sections. It took 20mins to transfer.

After we've upgraded to version 21H2 (even happening on version 22H2), we are getting on average 1000-2000 NAKs per failed setion. We get a failed section every 10-15 sections. It took 40mins to transfer.

So, the only change is the Windows 10 upgrade.

We tried to set the buffer size (to 2MB) and transfer rate but nothing seems to help.

Does anyone experience a similar problem? If so, how do you resolve your issue?

[Robert Bui]

Strange that on the computers that have high NAKs, there are two processes accessing the download file (see attached): one process is uftp.exe and the other process is System. Both constantly appearing on the Resources Monitor doing disk access.
While on the computers with low NAKs, onlythe System process accessing the download file. Maybe there is an uftp.exe process but it is so fast that not appearing or appear for a very short time ont eh Resources Monitor screen.

[Robert Bui]

Looking at the high System Interrupts, I should have investigated the cause of that.

Also, setting the UFTP log level (-x flag) on the client side to 4, I've found the client missed a whole section at regular interval.

So, most likely the network is the issue.

Downloaded the latest version of the network card driver (12 months old) and upgraded from the current version (4 years old), immediately saw a huge improvement.

No more NAKs in the 10, 000s. I am seeing a lot of NAKs < 100, with occassionly NAKs below 3000 (~10% of the time).

Thus, always try to use the latest version of the network card driver.