On a small college campus we have a VLAN setup for the computer labs. These machines get assigned IP addresses in the 192.168.7.xxx range. In the server room, all of the server are on the default VLAN and assigned an IP address in the 10.1.1.xxx range.
For the most part this works, but the lab machines are unable to connect to one of the servers. They can't even ping it. They can talk to other servers on the same switch as this server just fine. At first I thought it might be a vlan issue, but I changed the server port vlan to match other known-working ports with no effect.
I don't think it's a firewall issue — non-lab machines work just fine.
The server also cannot ping the labs, so it's definitely a problem in both directions.
I just tried tagging a couple lab ports for the server's vlan (lab vlan is untagged), but that didn't work (didn't think it would, but I had to try).
To be clear: the lab can ping another server on the same switch and vlan as the problem server. The other server it not on the same switch or vlan as the lab machines. So I know I can send pings through the network, including all trunks, as far as the destination switch. It's got to be something different with the server or port. Except it's not just this one server.
The problem gets weirder. I have a third server on the same switch as the other two. This server has multiple NICs. I can talk to the server on one nic but not the other. It is also a VM host, and I can't talk to any of the hosted VMs.