Still with connection problems some days.
If I connect through my 4G mobile phone, it works.
My ISP says that maybe LFS is not prepared for IPV6 (4G gives Ipv4 and router Ipv6)..

IPV6 is just bad for online gaming no matter the game. From Battlefield 4 and Fornite BR and STW along with others i have played, using IPV6 results in an unstable connection in the way of packet loss + fluctuating ping

As soon as its changed to IPV4 its stable and low ping

"if you have IPV6 turned on, DNS lookups are 2 to 3 times slower than with IPV4. That's why it seems as if your computer has "trouble connecting" to web sites. When you initiate a connection to any site, the first thing it does is look up the IP address in DNS.

DNS lookups are slow on IPV6 for several reasons.

First, DNS is currently handled in serial, not parallel. The IPV4 lookup is always handled first, then the IPV6, so it takes at least twice as long.

Second, because the IPV6 lookups are less frequent, they are not cached as often on the DNS server, causing further delay."

Also IPV6 is not supported by either many ISP's or as you say possibly the gaming servers

Just because your IPv6 connection is bad, doesn't mean everyone has a bad IPv6 connection.

How you describe how your DNS works is also specific to an implementation, not how DNS works in general.

But yes, LFS does not support IPv6, so if your router only gives out IPv6 it's not going to work. If it gives out both IPv4 and IPv6, the IPv6 part will have absolutely no consequence for LFS.

On the other hand, if your ISP is reporting that "maybe LFS is not prepared for IPv6", yes, that's true, however they may be using CGNAT for IPv4, which could well be causing issues. But that's not IPv6's fault, not LFS.

Quote from PeterN :

But that's not IPv6's fault, not LFS.

So where is the fault? The CGNAT?

Is there any sense to check for these options?
http://testingfreak.com/change-enabledisable-ipv4-ipv6-computer-windows/

I don't think so. I've tryed disabling IPv6 but still falling from server.
Wait, I'm not so sure, testing...