I use foam sound deadening panels from Amazon. I used 3M contact adhesive to stick the panels to plywood panels and hung them on the rack and placed on the top. I also made a panel that sits behind the rack to reduce the sound reflected off the wall. Been running this way for nearly a year.

I use pfsense CE. I am a bit worried that Netgate will be less interested in maintaining the community edition now, but it just works. I don’t need a lot of bells and whistles. So I’m staying put until I see a decent reason to switch.