No way, first we are talking about a high school, not something with university resources.
Then those were the days of Novell NetWare, and yes one of the labs did had a couple of them, not all, connect via Novell.
As for the Xenix tower, as mentioned, it did not belong to the high school, rather the teacher would bring it along with him from his main job, kind of renting it for the lab classes.
So nothing that could ever work in a permanent setting.
Just wondering why they didn't turn the DOS machines into terminals or ethernet / network to connect to the Xenix PC tower.