How to connect with computer on network

FYI: Long-time linux user. Familiar with command line.
I've used a mac mini for one month. Network connections are thus
far eluding me. Some times I see other computers in the local network
on finder and sometimes I don't. It seems totally arbitrary.

What is the proper way to do this? Right now, there are three other computers,
all linux - one my local network. And right now, I can't see any of them
in finder. Not so long ago, I could open finder and see all of them there.
I.E. The Shared item is disappeared from the sidebar.

URLS to documentation are welcome.
thanks
tim

Shared in Finder sidebar disappeared

Did you ever find an answer to this situation? I have the same thing. This is my first Mac, I have a network with 5 other PC machines all shared. About a month after owning this iMAC the shared computers started intermittently disappearing and a restart would bring them back. Not anymore, they are permanently gone now.
I read about a command-K trick and that worked for a while but after the iMAC goes to sleep the connection is lost. I have no problem connecting to the internet.
I have turned on all 3 shared choices in Finder Preferences, I have swapped out the switch on my LAN, I changed the CAT 5e cable, I can ping the other machines successfully I have search forums, and MAC support and I cannot find a solution.

I'm sorry. I never did find a solution, just a work-around. That, is to use the
Connect To Server dialogue from find and just put in the URI :
example 1 : Computer barbara, folder barbaras
or with an IP
example 2:
From the linux boxes, I just use the file browser - and it just works.
did you try the URI route?

Share missing from Finder Sidebar

I did do that through the command-K feature and it does work. It's temporary. Once the machine goes to sleep then I have to go back and reestablish but at least it works. It's just so odd that for nearly a month it was there then it stopped showing.

It only works in Finder however, If I'm in photoshop looking to open a file on one of the network computers, none of the shared computers show even after I establish them via command-K, but if I go back to finder they will still be there.

In searching for answers I see this problem goes back to early 2007 and at least 3 OS's back. Seems this is the apple "achilles" and not getting fixed with upgrades.

I'll keep looking, thanks for the quick response.