Hey,
I've bought a USB 3.0 10/100/1000 Ethernet adapter with an AX88179 chip from UGREEN (https://www.amazon.de/UGREEN-Netzwerkadapter-Gigabit-Ethernet-Ultrabook/dp/B00MYTSN18/ref=sr_1_3?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=AX88179&qid=1588337286&sr=8-3/ "Amazon") as capture device for my Win10 client. It's connected to a span port of an Netgear GS108Tv3 switch.
When I did the first capture I realized that there are a lot of "Previous segment not captured" messages in different TCP streams. So I started a second capture on the client side interface to compare the captures. The capture of the client looked fine. No errors or drops. But the capture of the USB adapter showed about 200 "Previous segment not captured" messages in one minute of 200 kbit/s traffic.
I've already did the following troubleshootings:
- Changed driver of US Adapter to original ASIX drivers -> same behaviour
- Checked adapter with another client -> same behaviour
- Started capture with the internal on-board-LAN port of my client on the same span port -> no "Previous segment not captured" messages. Conclusion: Span port is fine:
- USB adapter works fine as LAN interface. 952 Mbit/s throughput (iPerf3) without unusual error frames.
- Disabled all energy-saving and offloading options of USB adapter -> same behaviour
- Captured with dumpcap.exe. -> same behaviour. The summary at the end says "No lost pakets"
Now I'm not sure if the adapter has a defect, or if something blocks the missing pakets. Use anybody else the adapter from UGREEN? Or has anybody an idea what's going wrong here?
Thank you. Jas