+ 0 Votes More info chris 3 years ago Thanks for the replies. I was just being a lazy typist using the term PC for Windows. The connections are all wired CAT 5 through a 24 port gigabit managed switch. Ubuntu server unit is connected to the switch in a 2-port LAG (NIC bonding 802.3ad). No domain - just one Workgroup. As I mentioned, all the units can connect to each other just fine, but the Windows units can't consistently connect to the Ubuntu server (mostly cannot connect, but can connect once in a while). I was wondering if it might be some kind of network speed differential problem, given the link aggregation I set up for the server. But the Macs & Linux zoom on it, and I configured it for auto-negotiation. And I get the same results whether a Windows NIC is 100 or 1000 mbs. Another possible suspect: for network browsing, I have Samba set up as WINS server, Domain Master, Local Master, Preferred Master, OS level 33 and allow all hosts.