Love my Plugable devices. have around 25 of them for my companies. However I ran into a problem as I just updated my home network to 1 gigabit speeds. Techs left my house getting 985 mb download. However I can not get my SP4 connected to the ud-3900 to get over 300mb. I actually had the same problem when my speed was at 400mb from my ISP.
I am just worried my plugable ethernet driver is not configured correctly? Even if I plug it directly into the router I am not getting the speed. With the SP4 there is not network plugin of course so I use a Microsoft 1622 adapter to plug directly in. However it still uses your driver i believe.
I have gone into the Ethernet driver and switched it over to 1 gig full duplex but that didnt seem to increase the speed. Well maybe the first time after doing so it increased it, but could have been a fluke.
Before you ask all my network cables are cat 6. I have swapped out to make sure that is not an issue.
I ran the plugdebug and have the results ready to email