Probably an SFF PC off ebay for $60 or so + a 10G NIC. Could run Opnsense, or OpenWRT if you wanted to.

Extremely unlikely that wifi would affect it.

More likely a software crash or a hardware issue.

You’ll get better performance from a 7th Gen core i5 box with about 1/10th the power usage, those go for $80 or so usually.

The main downsides of windows for a server are:

• Forced reboots

• More RAM/Storage usage for the OS

• No options for ZFS or similar data protection software, storage spaces provides basic RAID but the performance can be fairly low.

• Needs a license

• Less general availability of self-hosted software, but you can run Docker for Windows as a way around that.

However there are some upsides, it’s very easy to set up and manage, SMB shares are super easy, and some backup software like Veeam B&R is windows only.

Only when I’m installing/removing hardware. Probably like once a year on average.