Our small business LAN has several (Windows XP) PCs that are experiencing very slow internet speeds. LAN speeds appear to be fine, testing around 90 Mb/s using iperf, but seeing internet speeds around 0.2 Mb/s. Most computers on our network are getting internet speeds around 2.0 Mb/s (we have two slow Qwest DSL connections going into a Linksys RV082 router with dual WAN ports).
This problem first started when we replaced an old 10 Mb/s hub with a new 100 Mb/s unmanaged switch (Cisco SR224G). The slow internet speed can be eliminated by putting the old hub back in line with the slow PCs. But going directly into either the switch or the router causes the slow internet speed to come back. Note that in either configuration, LAN speeds inside the network are great: 90 Mb/s (or 9 Mb/s when going through the old hub as you would expect).
What could the old hub (OvisLink Ethernet Hub 16+) be doing to the traffic that would so dramatically speed up our internet traffic to certain PCs? What can I check for to track down the cause?
We've run several virus/malware scans on both. These are relatively new (3 yrs old?) PCs with 100 Mb LAN ports built in to the motherboard. I haven't checked the duplex settings but if this were the problem, or if the cabling in the building is bad, how am I getting 90 Mb/s internally?
Also tried forcing one client NIC to 100-Full or 100-Half instead of Auto-detect. This didn't make a difference, the problem is still very reproducible.
Another clue: ping packets seem to be as fast as usual, but TCP is slow. At least on speedtest.net the initial ping is 75ms, right in line with what we usually get, but then the page just freezes up and doesn't even move. On occasion it does work through to the end where the results are something like 0.1 Mb/s.