I’ve done a lot of things related to computer networking. My community college’s IT program really focused on it. I took classes on CompTIA Network+ and Cisco CCENT/CCNA certifications. I never paid to get the certification exams, but I did use Cisco IOS a lot. I’ve also built custom routers using pfSense and DD-WRT.
The above photo shows a router I set up for someone I know. I installed DD-WRT on it, which is Linux-based router firmware that allows you to get security updates well after the manufacturer abandons the device. This is important, because router and IoT botnets are increasingly common. It's not hard to use Shodan or masscan to find vulnerable devices, or even just things with weak or default passwords. I got a fan breakout board to use PC DC fans with an AC adapter to cool the router and modem. There is also a dual-band Ubiquiti access point above the router.
I’ve set up network printers, file servers, routers, modems, switches, powerline ethernet, IoT devices, wireless access points, and more. I know about VLANs, subnets, network attacks, IDS/IPS, networking imaging, netBIOS, routing protocols, remote access, firewalls, Wireshark, routing and switching on Cisco devices, and things like that.