Score:0

D-Link DUB-E250 2.5Gb USB-C network adapter not running at full speed

cx flag

I am trying to use a D-Link DUB-E250 network adapter but it doesn't run at its full speed. I'm not sure if it's even possible but I'd like to dig in a little to see if I've missed something. Perhaps needs a driver that I don't have.

Firstly, while it's a USB-C device I'm running it through a USB-C to USB-A adapter. The other end is a QNAP 2.5Gb switch which certainly works for a QNAP NAS which is attached.

I've tried to interrogate the network device but while it is connected and functions it doesn't give much away.

# lsusb
Bus 001 Device 002: ID 2001:b301 D-Link Corp. DUBE250 2.5GbE Adapter

# lshw -class network -short
/1             enx7898e8fd7639  network        Ethernet interface

# ethtool -i enx7898e8fd7639
driver: cdc_ncm
version: 5.11.0-40-generic
firmware-version: CDC NCM
expansion-rom-version:
bus-info: usb-0000:00:14.0-3
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: no

Does anyone know if running this at full speed is even possible? Or other commands I can use to interrogate in a bit more detail?

ChanganAuto avatar
us flag
It can only achieve 2.5Gb if connected to USB-C (3.2 gen).
cx flag
Well that's the end of that. Thank you
guiverc avatar
cn flag
I see no OS & release details provided; basic diagnosis requires a starting point and knowing your OS & release is the easiest way for us to know your software stack & what you may/may-not have installed. Please provide (Ubuntu LTS releases have two kernel stack choices [*drivers* are actually kernel modules]; but we currently don't know if that's available to you, or you're using the latest stack choice..)
Score:0
cx flag

I resolved the issue by buying a 2.5Gb adapter with a type-A connector. This works flawlessly.

I believe, as has been pointed out, the issue was using the adapter. I don't believe it to be a fire hazard however. That's a bit extreme and I'd be surprised if there was any examples of such a thing happening.

I will keep the original device for use where there are USB-C sockets available.

Score:0
it flag

I found your problem. It's right here:

while it's a USB-C device I'm running it through a USB-C to USB-A adapter.

USB-C to USB-A adapters break the USB specification, they are explicitly forbidden in the USB spec and using them is a fire hazard. Smash that USB-C to USB-A adapter to bits with a hammer and burn the remains so it no longer poses a threat to your hardware. I'm serious, this is a hazard to your hardware and will continue to be a hazard until it is gone. There is ample evidence of people seeing expensive computers being rendered worthless because adapters like these bypassed protective systems built into the USB spec. One such protection against damage was to explicitly forbid these USB-C to USB-A adapters.

There's likely other issues involved here on why you are not getting the expected behavior from your D-Link Ethernet adapter beyond this USB-C to USB-A adapter but I'd rather not speculate on those as they don't concern me much. The problem that concerns me the most is your use of an adapter that does not, and can not, comply with the USB spec.

ChanganAuto avatar
us flag
Can you post some link / online resource / academic paper that corroborates your assertions about the adapters? Your answer will be tremendously improved with such.
it flag
@ChanganAuto See Section 3.1.4 and Table 3-3 of the Universal Serial Bus Type-C Cable and Connector Specification, link to document: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf
ChanganAuto avatar
us flag
Well, the specifications do not exactly corroborate the fire hazard assertion.
it flag
@ChanganAuto " Well, the specifications do not exactly corroborate the fire hazard assertion. " Would you agree it shows the adapters are explicitly forbidden? Is that not enough to suggest it is a bad idea to use such adapters?
ChanganAuto avatar
us flag
I agreed with that even before you posted this answer. Now, between a "bad idea" and a "fire hazard" there's an entire ocean of possibilities.
it flag
@ChanganAuto See section 2.2 of the USB Type-C document I linked to above. In there you will find this, "USB Type-C receptacle to USB legacy adapters are explicitly not defined or allowed. Such adapters would allow many invalid and potentially unsafe cable connections to be constructed by users." Given the experiences people conveyed in Amazon reviews of these adapters "potentially unsafe" often translates to "starts fires".
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