Addtional info: boot goes fine, press f12 to network boot no problem. Next computer says xxx \boot\x64\pxelinux.com (this file loads fine, it says version number and some other data)
Then it hits the problem: failed to load vesamenu.c32. It does not matter what i write to default file that sits in pxeconfig-directory. Seems that file newer gets read.
Now because pxelinux.com file loads, doesn't that mean TFTP-connection is established? Or does it happen after this file?
All the necessary ports are open through the firewall, if I have time tomorrow will examine connection with Wireshark.
All I need is simple incructions to build environment where I could deploy Linux installations as easily as you can deploy Windows to different machines through network boot.