[17.66] Constant disconnects (jumps) in LAN (modded)

[xPucTu4]

We have dedicated headless server and 2 PCs in our LAN.
While playing one of the PCs have constant disconnects due to jumps.
I made screenshot of the 2 screens and I can't see what should be the problem.
All 3 PCs are good enough to keep the UPS.
The problems are on Intel 4770K (not overclocked) at 3.5GHz with 16G ram.

Edit: I forgot to mention the version is 17.66 but I have this problem since around version 17.30 or maybe earlier.

[Loewchen]

See Performance issues in the local FAQ.