I have a client with a small (5 old Win98 workstations) network. They have no server and had an old ISDN connection that seemed to work periodically but have long timeouts. They upgraded their link to a Birch T1, but are having the same issues, Internet connectivity up and down.
They recently added antivirus software to their PCs but they seem to scan clean. I plugged a laptop directly into their gateway and it performs fine. If I run it through their cabling, it seems slower. If I plug other network devices back in, it is even slower. Tracerts show increasingly slower responses and it seems like DNS is timing out.
We had their cabling vendor come in and test cabling, but they say it is all OK. I plan to swap their switch, but am looking for other ideas and tests. Any suggestions?