I recently obtained a Dell t620 that I've rack mounted, and I'm using to upgradey homelab. I'm also thinking I should upgrade my routernsince I'm having to reconfigure a lot with the new server(I have a 12 year old Netgear wireless router).
Forgot to mention that before I got the R210 II, I had a Ubiquiti Unifi USG-PRO-4. It worked okay but the hardware is pretty low end. You get a nice pretty UI and many more options/configuration compared to a consumer router, but it's hamstrung compared to what you can do with OPNsense/pfSense IMO.
I ended up finding an old 5 GB sophos router that I was able to flash pfSense onto, it's not rack mounted, but was way cheaper than spending $500 on a ubiquiti.. I like it so far, but need to do more testing