I have an office of 10 desktop computers and 1 server. All of the desktops are connected to a Netgear JFS516 100 Mbps switch. The server and the switch are connected to a Linksys E2000 1 Gbps router. There have been no recent changes to the network, but most of the desktops (a specific few far more often than the others) have been dropping down to 10 Mbps after logging in, mostly in the morning; rebooting seems to fix the problem for the day. Some of the computers, mostly notably mine (which is closest to the switch) almost never experience this problem.
All of the desktops are the same, Dell Vostos with Broadcom NetLink Gigabit NICs, and all have the same configuration. I ran and terminated all of cable (CAT 5e) myself about 4 years ago and recently reinspected the cable visually and electrically: the cables don't look damaged and each of the pairs in the cables are correctly terminated per TIA/EIA-568-B.
I put 3 of the desktops that were encountering this problem on a different switch, but they still exhibited the same behavior. I've been logging the link speed of each computer every 5 minutes for a few days and am unable to see any pattern other than it normally happens in the morning when they first wake their computers from sleep and log in.
I'm at my wits' end, so please suggest anything I can do to find the source of this problem and fix it. Thanks!
It's been one week since I disabled power management so the computers wouldn't go to sleep/suspend mode (they are still shut down at the end of the day). In that time, I have not had any link speed issues on any of the computers. I am still uncertain as to why resuming from suspend would cause link speed issues, especially only in certain sections of the office. My best guess at this point is that possible cable issues (age, interference, distance, etc) play a factor along with suspend in creating the lower link speed. Thank you to those who took their time to help me out!