Re: WD15 and Latitude 5280 - Slow internet speeds 8mbps
You definitely do not want to have the switch port linespeed and duplex hard-coded with the client NIC on auto negotiation, or vice versa. That needs to be consistent on both ends of the link. Even hard coding one side to the configuration it would have auto-negotiated anyway can create problems if the other side is actually on Auto.
But taking a step back, if you want a reasonable chance of getting helpful assistance here, I would strongly suggest cutting down your number of test cases. It's simply too difficult for anyone to follow your posts. As you said in one post earlier, you should probably focus on one problematic configuration to figure out what's wrong there and then apply that fix to other systems. Every system should obviously be able to run at proper speeds with either dock, at least when you're using appropriate ports and AC adapter wattages. So here is what I should suggest doing in order to help narrow this down and make it reasonable for people to try to help you here:
- Find a specific system and specific WD15 dock that work reliably when used together -- call them System #1 and Dock #1.
- Find another system of the same model and OS, and another WD15 that do not work properly when they are used together, even when using the same Ethernet cable and wall jack as above. Call these System #2 and Dock #2.
Once you've established that Setup #1 consistently works and Setup #2 doesn't, connect System #1 to Dock #2, and then System #2 to Dock #1. See whether either of those configurations works reliably. Further troubleshooting and isolating of other variables (system/dock firmware, driver versions, etc.) should proceed based on the outcome of those tests.