Primary Server & Infrastructure
Our primary home server is currently an Intel core i5 based system running Linux, based on 64 bit OpenSuse, built in to a 2U rackmount case.
This runs most of the 24/7 systems, which include HA/Security, Asterisk PBX, Primary Mail Server with MailScanner, Directory Services, Web server, File & Print, etc. etc. Many other services are running on various Raspberry Pi's - Zero, Zero 2, 3b+, 4 and 5.
A current project at the time of writing is to explore replacing the primary server with a Pi 5.
The server lives in a 12U rack in our loft which has been structurally boarded out and has also been insulated under the eaves as well as conventionally between the ceiling joists. This was both to increase the insulation efficiency of the house during winter but also to help reduce heat gain during the summer.
Block diagram (simplified) of HA Infrastructure