Cannot get 2.5 Gigabits per second Internet Speed on v Workstation

[Z9Mini]

I have a  Z2 Mini G9 Workstation and recently upgraded to 2.5 gps AT&T fiber internet. I canot get more than 990 GPS running both OOkla Sppedtest as well as NPERF TEST.  The AT&T tech ran new CAT 8 ethernet cable from the AT&T router into his speed test device and recorded close to 2.5 GPS. When we ran same ethnernet cable into the ethernet jack on back onf my Z2 Mini G9, we got 990 GPS max.

I went into the Windows 11 device manager and changed the settings Under Network Adapters > RealTek Gaming USB  2.5GbE Family Controller > Properties > Advanced > Speed & Duplex to 2.5 Gps Full Duplex, then restarted and same 990 MAX speed test and NPERFTEST.

I also tried a Sabrent USB-C to 2.5 Gigabit Ethernet Adapter  in both side USB-C ports and connected the ethernet cable into the adapter dongle , restarted, and same 990 GPS.

How do I get 2.5 Gps internet on this Z2 Mini G9 runing Windows 11?

[banhien]

@Z9Mini 

Its specs

               https://h20195.www2.hp.com/v2/GetDocument.aspx?docname=c08109685

It ONLY has (1) 1GbE LAN  (item (6) on page 2). 990 Mbs is very close isn't it.

Regards.