@stephenw10 it shows up as USB adapter with 10/100/1000 speed options.
Anyway i have figure it out. So as I said, I used intergrated NIC for WAN interface and USB to ethernet adapter for LAN interface. First I tried plugging in ethernet cable to my intergrated NIC Intel(r) ethernet connection i219-lm adapter on wich I had 100mbps speed.
I went testing that interface and noticed that intergrated NIC on my laptop was always the same speed (even if I pluged ethernet cable to professional switch - Juniper or just dummy switch). But if I added another USB to Ethernet adapter and pluged this one to my laptop it worked with 1Gbps.
So I went and reinstalled drivers for my laptop NIC, installed all updates and nothing changed.
I went testing on another laptop - same story. I couldnt get 1Gbps speed on integrated NIC and it worked only if I used USB to ethernet adapter for laptop.
Then the last thing that came on my mind was that i changed ethernet cable to 6a category and ... it started working on 1Gbps.
I'll do some more testing and reasearch but for now its working with 1Gbps.
Thanks for help!