Not getting above 1gb at best w Dell XPS15 (edited) thunderbolt 4 ports backward compatible w usbc3

cat 6a 30 foot long cable going to the 2.5gb jack of Ubiquiti UDM Pro Se.
ISP 10gb. Always get at least 3gb up and down at my intel 10gb nics in other pcs

if connected to the 2.5gb jack on the UDM i get under 300Mpb

if switch the cable to a a 1gb jack on the UDM, I get close to 1gb

UDM 2.5 port set to auto negotiate. Forcing it to 2.5 didn’t help.

cabled to a Ubiquiti UDM Pro Se firewall, 2.5 gb autonegotiate rj45 port, max i get is 125 mbpss up and down out to internet.

if I connect to one of 1gb rj45 ports on the UDM, I get close to 1gb both directions.

(if i connect to a 10gb switch that is connected to the UDM 10gb jack, I don’t think I get any connection, but for sure <1gb.)

pc is Win 11, new Dell XPS15, thunderbolt 4 compatible data usbc port. all testing using same port on the XPS15, same cat 6a cable.

driver is realtek as shown in Win 11 programs and featur.s

Device Manager 1153.4.211.2022 USB Gbe Family control no 2

also a USB 2.5GbE Family Controller same driver ver.

(am posting because i only created a support ticket late Friday)

I’m now thinking the problem is with the Ubiquiti 2.5gb rj45 port in some way, not my 2.5 usbc Plugable nic adapter because I get similar behavior using an OWC 10gb auto negotiating thunderbolt 3 adapter, with all updated drivers.

With either of those adapters , if I connect to the 10gb port on the Ubiquiti, I consistently get expected throughput of about 1,900 on the Plugable 2.5 gb adapter and 7,000 on the OWC 10gb adapter at the Dell XPS15 using Oookla.


Welcome to the Plugable forums! To best assist here with your USBC-E2500 its best to reach out to us here

Per your troubleshooting if this bandwidth issue is occurring with multiple ethernet adapters there may be an isolated issue with your Ubiquiti host device. In your email to our support site please reference ticket #381683 in your initial email. I hope to hear from you soon.


Product Owner
Plugable Support

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