UD-3900 impacting ethernet speeds

Hello,
I have two laptop setups, both laptops are HP DF0023CL’s (3.0 USB ports) and two UD-3900’s.
I am connecting them to a Netgear R6700v3 router and getting 1GB internet service from CenturyLink
that has never measured more than 800mbps on speedtests. I am using cat5e or cat6 cables for the connection to the router. I have applied the latest Pluggable driver 9.3 M1 (version 9.3.3147.0) to both.

I am having the same problem with both setups. If I connect the laptop directly to the router I get download speeds generally above 700mbps. If I am connecting the laptops to the docking stations I typically get download speeds between 250-300mbps. That is quite a dropoff that I would like to close so I am approaching something closer to the 700mbps speed.

I forgot to mention that I had seen in a related post to change network adapter “Speed and Duplex”
setting from Auto to 1 gbps full duplex, which I tried on both laptops and it didn’t help.

Hi,

Thanks for posting!

Thanks for great detail provided. To be transparent, networking issues such as these can be difficult to solve as there are a lot of potential factors at play and the networking infrastructure varies depending on the environment. That being said, you provided a lot of specific details so I’d like to do my best to help.

Could you please see the following additional questions?

  1. Can you confirm that the original USB 3.0 Type-A to Type-B cable is being used?
  2. The R6700v3 router has four LAN gigabit Ethernet ports. Do all four Ethernet ports perform the same?

Additionally, I’d like to request some logs from one of the HP systems to best investigate further. Could you please keep the Plugable dock connected (with the Ethernet cable connected to the dock), then navigate to our PlugDebug tool and follow the instructions there?

This will create a ZIP file on your Desktop containing system logs and information. Please send these logs to us directy at support@plugable.com with reference to case ID 294982.

Thank you for giving us a chance to help!

Mitchell

Hello Mitchell,

Thank-you for the quick response.
Just sent in a logfile with the network settings checked.
You inquired about the following:

  1.        Can you confirm that the original USB 3.0 Type-A to Type-B cable is being used?
    
  2.        The R6700v3 router has four LAN gigabit Ethernet ports. Do all four Ethernet ports perform the same?
    

Yes we are using the original USB cables on both replicators. We’ve also tried swapping the ethernet cables around.

Made sure to try all four ports on the router. It was interesting to see some of the variance between ports when
doing the same test. That being said, direct connecting from the laptop to the router was consistently many times
faster than when using the UD-3900 connected to the router. For example:
port direct pluggable
1 779 188
2 423 191
3 505 161
4 453 109

I appreciate the additional information as well as the log files you sent over.

Looking through the log contents, the first thing that jumps out at me is the existence of NordVPN. We haven’t tested our dock’s Ethernet connection through a VPN, so if you haven’t tried already, please try temporarily disabling or uninstall NordVPN to ensure it does not have any impact on the dock’s wired Ethernet connection.

Next, while simple, please do restart your router to ensure its working at a clean refreshed state.

Looking forward to hearing back from you.

Thanks!

Mitchell

Rebooted the router, but that didn’t change anything. It had been rebooted recently anyway just prior to when I made these posts.
Understand your concern about the VPN software. That generally is an app we use more on our mobile devices when we are away from home. On our laptops it is usually not connected except for occasional use where we disconnect afterwards. That being said, I saw where there was a NordVPN background service that seems to always be on. So I went ahead and removed the VPN software and rebooted the laptop. Still didn’t make too much difference. When connected to the replicator speeds were in the 300-380 mbps range. Immediately plugged ethernet directly into the laptop from the router and got a speed of 683mbps.

thanks

Thanks for getting back to me.

Looking further into the log contents, I’m not seeing any other obvious potential factors that would explain this throttling. The logs indicate a successful negotiation of Gigabit Ethernet speed.

To help further isolate the issue, would it be possible to connect the Ethernet cable from the UD-3900 dock directly to your modem (bypassing the R6700v3 router). I do understand that when you have the Ethernet cable directly connected to your system, you get normal speeds, but this just helps us understand where conflict could lie with the dock.

Thank you!

Mitchell

Hi Mitchell,
Sorry it took a little while because my CenturyLink modem/router was running in bridged mode so I had to do a little reconfiguring to be able to connect directly to it. The following tests were done within 45 mins of each other.
laptop-ud3900-netgear router 329 mbps
laptop-netgear router 734 mbps
laptop-ud3900-centurylink modem 268 mbps
laptop-centurylink modem 821 mbps

Thanks for your update and diligence, and no worries about any delays.

Based off the testing so far, the culprit likely lies more downstream, such as with the dock. What if you try disconnecting all USB devices connected to the dock (including the WD My Passport drive), then testing once more?

Thanks!

Mitchell

Okay disconnected everything. The only things still connected to the dock are the ethernet connection, the power connection, and the USB connection to the laptop. Speed still came in at 320mbps. I immediately moved the ethernet connection from the dock to the laptop itself and speed came in at 757mbps. I haven’t tried this test with the other dock, because they were purchased at the same time and so far they have been behaving the same with everything else. If you do feel a test with the other dock would be important or if you need another set of logs let me know.

thanks

Hi Mitchell,
Got the new ethernet adapters today.
Here is what I did:
Rebooted the router
Rebooted PC1 & PC2
Ran speedtests - 297mbps on PC1 and 287mbps on PC2
Plugged the new adapters to the front (3.0 port) and moved the ethernet cable over to the adapter
Rebooted PC1 & PC2
Ran speedtests - 611mbps on PC1 and 682mbps on PC2

So I will let you ponder those results. Its nice to take advantage of the full speed capabilities, but I would be concerned if this is the permanent solution as based on what you told me all the back USB ports are 2.0 and if I use the new adapter on the front that leaves me with just a single 3.0 USB port available and that leaves me a little thin on the 3.0 side.
Thanks,
Dan

Hi Dan,

Thanks for the update and apologies for the delays in a response.

It’s clear from the results that there is something going wrong with the dock’s DisplayLink Ethernet interface. The adapters use a Realtek controller, but since the connection is still going through the UD-3900 dock itself, that isolates us away from a host cabling issue perhaps operating at USB 2.0 speeds.

We’re in the process of escalating this issue – I appreciate your patience in the meantime. This thread will remain open until I have an update for you.

Thank you!

Mitchell

Hi Mitchell,
In regards to your latest email, I was already at build 9.3.3147.0 of the DisplayLink. I had run the cleaner tool and upgraded the driver prior to my original post. But, in order to be thorough I ran the cleaner after uninstalling and then re-installed the download and hooked everything back up again. Results were pretty much the same 285mbps for the onboard adapter and 620mbps when I was plugged into the Realtek adapter.
Dan

Hi Dan,

I did see that the latest version was already installed, but it was worth a clean reinstall just to ensure the driver is in a good state. Thank you for working with me there.

We have this issue escalated with DisplayLink and will get back to you as soon as we hear back.

Thanks for your patience.

Mitchell

Hi Mitchell,
It’s been a week since last contact.
Any updates on where my issue is headed?
thanks,
Dan

Hi Dan,

Certainly haven’t forgot about this issue.

We have the ticket escalated to DisplayLink and they are still looking into the issue.

Thanks for your patience.

Mitchell

Pinging the thread as it was about to be closed (20 days since last response).

Hi Dan,

Thank you! (I can also re-open the thread, so no worries)

I requested an update from DisplayLink so hopefully I’ll have more information for you.

Thank you!

Mitchell