Summary:
I’m getting 150-300mbps download but full 1600mbps upload for any 2.5gbps ethernet adapter built in or behind my corsair thunderbolt 4 docks and cannot figure out why.
Setup:
att fiber > cat 6 > firewalla gold plus 2.5gbps router > cat 6 > Eero 7 max > wireless backhaul > Eero 7 max > cat 8 > corsair TBT200 2.5gbps ethernet or startech 2.5gbps ethernet adapter ( the one with the properly functioning chipset for macOS) > thunderbolt 4 cable to M1 Pro or m2 pro MacBooks ( I have 2 tbt200 docks in same configuration)
Attempts:
If I use the startech ethernet adapter directly plugged into one of the 3 thunderbolt 4 ports on my MacBook directly I get full bidirectional speeds of about 1600mbps due to it being a wireless backhaul (its my only options sadly.)
If I connect the startech ethernet adapter through the corsair tbt200 thunderbolt 4 dock I get the same speeds of 150-300mbps down and full upload speeds which match the docks built in 2.5gbps ethernet port.
I also tried lowering my display settings down to 1080p60 SDR and it does not help the download speeds.
I have never seen something so odd that upload speeds work better than download speeds just by using a thunderbolt dock.
Any advice or direction would be appreciated because Corsair just keeps asking for pictures and doesn’t have a clue how to help me.
Have you tried a different cable from the tbt200 docs to the mac?
Are there any software settings you can configure because that’s what it sounds like to me, specifically max download speed set to 100MB vs full or auto negotiate .
It sounds really like it is going into usb2.0 mode and would be something i normally expect when a dock is using displayport alternate mode. But that is not the case if it runs on thunderbolt.
The one time i’ve had an issue like this was with missing drivers. If it is possible i would still check and download drivers, i’m guessing there is probably a realtek 2,5gb chip in it? (i had a PCI-E 2,5gb card that had slower downloads than upload and it was solved after installing drivers)
macOS has some software settings for the ethernet adapter to be automatic or manually assigned up to 2500Base-T full duplex. I have tried both automatic and manual. I have also checked my router/firewall to ensure nothing on it should be limiting throughput.
I am using Kondor Blue thunderbolt 4 cables that are 2M but I don’t think they are active cables so that may be causing the oddness. I have to wait for the 1.8M Apple Pro Thunderbolt 4 cable that I know is an active one to rule out the cable to the computer. I misplaced the original 1ft thunderbolt 4 cable that came with the dock in the move it seems unfortunately.
and Corsair does not provide a driver outside of their utility and it makes zero improvement with or without the utility.
The display is just a DP 1.4 Asus 42 inch OLED so its not TB all the way to the display so maybe that is the issue but why would System report a full 5Gb/s USB link speed?
the 0x8156 does seem to be a Realtek chipset and Im not sure there are macOS drivers for this.
Even still the Startech adapter is what confuses me because It behaves differently behind and in front of the Corsair dock so Im hoping its the thunderbolt 4 cable to the MacBook that is all that’s causing the issue.
display was detached and the download speed is at 700Mbps and the upload is still at 1500Mbps so I doubt it is alternate mode that is causing the issue.
I have already done usb3 gen 2 ssd tests with the same tbt200 thunderbolt docking station when I did my usb hub tests for another post I shared. I easily reach 900MBps reads and writes to my Samsung T9 External SSD. that is same as the MacBook Pro port speeds and is way faster than 700 megabits per second since the drive test was in 900megabytes per second so beyond 8 times faster usb speeds behind the hub.
With the Realtek chipset being used and the fact that macOS does not allow third party drivers much anymore and with macOS Sonoma providing built in os support for 2.5gbe chipsets and the fact that there was never a Realtek supplied driver for the last several versions of macOS and so they do not have an ARM compiled driver to be installed for my current operating system, I have not bothered trying to install a driver from 5 years ago.
I also tried the apple pro thunderbolt 4 cable and it does not fix the issues either.
I found a mile long thread online about other users having a similar experience with the ports on the back of the Apple Studio Display.
Essentially they said they could only get gigabit speeds if they used certain 2.5gbe adapters. Also it only was an issue going through the Apple Studio Display and only on M-Series apple chips. So I think it’s a compatibility issue with the macOS supplied Realtek drivers when connecting through a hub of some kind.
I am waiting for a 10gbe thunderbolt adapter to see if using thunderbolt may help reach full speeds but Im rather disappointed that it will likely be unsolvable because of some bug with the apple supplied ethernet drivers.
Since the Corsair tbt200 is a thunderbolt 4 dock and had an extra thunderbolt 4 port I ordered a sabrent thunderbolt 3 to 10gb Ethernet adapter as it was the cheapest one I saw on Amazon and sure enough it reaches full speeds bi-directionally upwards of 2200Mbps, which means it is even faster than the usb adapters.
I was nervous because some of the reviews said it uses Realtek drivers too but opening system report in macOS it uses another driver altogether. It is also PCIe over thunderbolt so it makes use of a different protocol to talk directly with my MacBook through the hub.
So good news is I found a solution that is working and has the added benefit of being future proof for a while supporting up to 10gbps if my network ever supports that someday.
The bad news is I have to use thunderbolt for something usb should be capable of.
Also called Apple and their senior advisor essentially informed me that they likely won’t do anything about it since it is from a third party hardware which is what I expected.
Thanks for your advice though I think it helped me find a solution that works.
FYI I have this same dock with a M3 MBP. It’s only connected to a gigabit switch but I did verify that I am getting gigabit upload and download on my network with it.
Glad you were able to find a workaround! Let me know if you would like me to debug anything though.