Turns out that the added Acronis Cyber Protect Home Office was the fault for slow Ethernet speed.
New Latitude 5521 Ethernet speed ~ 400-500 Mbits, lower than connected to WiFi. I have a 1 Gbits internet. Other PC (old Lenovo) shows Ethernet speed ~940 Mbits when connected to the same socket. Any help?
New Latitude 5521 Ethernet slow