Both linux versions were complied from git. Windows version was updated to test build,
I just checked the settings and cl_maxpackets was set to 30 on the gog version. I made the same change on ioquake3 version and i still get around 40ms of ping.
When i connect both clients together (no dedicated server) they have very low ping, I will make some tests running the dedicated server on the slackware pc instead of the raspberry to see if there is a difference.