I setup (took over and spruced up, to be precise) this community specifically because of the time I've spent over the years browsing and relying on reddit.com/r/sysadmin for sources of information on tips/tricks, security exploits & patches, outages, and yes even the ranting about how our jobs all suck. (I like mine, for what it's worth.)
Come on down, ask questions, post what the sysadmin community needs to know about, or head in to get either sympathy or chastisement about why you haven't left your job yet. 🤣
I know there are many different front ends with which you can participate in Lemmy servers via the Fediverse, but haven't gotten into it enough to make a recommendation. I've just began checking out https://kbin.social which might be closer to what you're looking for?
I agree that the Lemmy UI isn't old reddit, but it's enough unlike new reddit that I'm comfortable with it. Sure it's got some 'wasted' / open space, but it works well.