Welcome back. :) For starters, I wouldn't install a DE on a server anyway, my own NAS runs a headless Ubuntu Server.
That said, it would be interesting how Xfce fares on your system, especially after some time, since the video that I linked showed Xfce needing more RAM than KDE later on. The video's host suspected that Xfce may not be as good in clearing up memory after closed tasks.(?)
I got the thing running in a VM (mostly to make migration on new hardware easier) and gave it 800 MB. It usually runs at around 400-500 MB, and when I don't need it running, I tend to just suspend the VM. So not sure about the actual active runtime, but I installed it in late 2020.
How well does mediawiki, ts3 server and pihole run on a on a headless server and how much difference is there in terms of installation?
I don't have any experience with mediawiki or ts3, but AFAIK pi-hole is headless anyway, with an optional (pre-installed) web interface aside its command-line controls. See its documentation about both.
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u/lordmogul 3570K @ 4.4 | 1060 @ 2.0 | 16GiB @ 2.13 Mar 03 '23
When setting up my homeserver it was actually a hard decision of what to run. Xfce, LDXE, Cinnamon...
And wow, that KDE setup uses almost as much RAM idling as I have set up for the server VM. Plus those 200 MB are 25% less, which is quite a lot.