I have a Windows 2003 Small Business Server SP2, that has been running without issue for the past 2 years. Last week we started using the Exchange 2003 functionality, (previosuly we had been using hosted Exchange). Since then we've been suffering from a very slow network. I initially thought this was due to the mailbox data which we exported from the online hosted Exchange, then imported into the users Outlook profile. However, all data has now synchronised between the users Outlook, and the Exchange server, but we're still suffering from a slow network.
We only have 25 users, running Dell OptiPlex 755 desktops, the Server is a Dell PowerEdge SC440, with 2GB ram, and 500gb hard disk, it has 2 network cards, one for internal LAN, and one for external internet access. We use the SBS server as a firewall, which only allows Outlook Web Access & VPN in.
We have 3x 24 port switches, 2 of which are 10/100mb, with 2 gigabit uplink ports, the 3rd is a full gigabit switch. The 2x 10/100 switches are connected to the gigabit switch via their gigabit uplinks.
Everything seems to run fine for an hour, then suddenly mapped drives won't open, files that are open on mapped drives won't save, and we can't browse the server. However, we can ping the server IP address, and it returns the ping. We can ping via IP & name. We can use the internet, which runs through the SBS server with out any problems.
I've tried switching cables over, updating NIC drivers, the LAN cards are configured with DNS correctly - the server uses its own IP & loopback, and the clients use DHCP which sets the server IP address as the primary DNS server.
What would cause UNC paths to fail, while PING & internet acess still works?