My Raspberry Pi 3 works as a CUPS print server connected to a laser printer, as a pi-hole DNS server to filter ads, and as a ssh entry point (with dynamic DNS). I would use a Pi zero, but Ghostscript is not too happy when printing large documents on a single-core processor with 512 MB of ram. I still have to find the time to set-up a backup server on it (and decide which software to use).