I solved the issues. Thanks ED. Wrote ticket to support and they help me found out that my ISP provider is blocking some ip addresses. cdn.digitalcombatsimulator.com and also update.digitalcombatsimulator.com
Now I'm using VPN and have no more problems to update.
Maybe it will help someone else.
Here is the list what to check if you have fails to connect servers:
Check if your windows auto tuning level is enabled by opening CMD with admin, then paste:
netsh interface tcp show global
if its not enabled enable it by:
netsh int tcp set global autotuning=normal
Check if the IPv6 protocol is enabled in the network adapter settings.
Try to manually change DNS server for IPv4 to free DNS from Google 8.8.8.8
https://www.howtogeek.com/164981/how-to-switch-to-opendns-or-google-dns-to-speed-up-web-browsing/
Try connecting an internet cable to your computer directly, bypassing the router.
If that doesn't help try using a VPN like Windscribe:
https://windscribe.com/
This VPN gives you 10GB of free bandwidth per month.
Also, if you have the opportunity, try connecting the Internet from a 4G smartphone.