Unidentified Network - Kerberus Auth Problem only with SSL and without NETBIOS

Could be related to the DNS implications in SSLVPN? You have DNS request routes in SFOS, thats not part of IPsec. Which means, if the Windows cannot figure out the domain after disable netbios, it could be the cause of your issue. Check the dns captures here. 

Hi LuCar, thank you for fast answer. I don't see any DNS request routes. Could it have something to do I did because of the issue in this thread?

iptables -t mangle -I POSTROUTING -s 172.20.10.0/24 -d 10.10.0.0/16 -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1300;

iptables -t mangle -I POSTROUTING -s 10.10.0.0/16 -d 172.20.10.0/24 -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1300;

Hi LuCar, thank you for fast answer. I don't see any DNS request routes. Could it have something to do I did because of the issue in this thread?

iptables -t mangle -I POSTROUTING -s 172.20.10.0/24 -d 10.10.0.0/16 -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1300;

iptables -t mangle -I POSTROUTING -s 10.10.0.0/16 -d 172.20.10.0/24 -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1300;

Essentially this looks to be a windows issue to be honest. I dont have much insights into this problem - You should check what kind of mechanism windows uses to check for discovery. 

https://serverfault.com/questions/814557/changing-windows-network-profile-from-domainauthenticated-to-public

Looking into this, it looks to be related to DNS. 

If it would be a windows problem why we have no problems with IPSec or in LAN with the same clients?

So basically windows is doing something like a discovery. Not sure what Windows does there and needs to be "reverse engineered" to get to the bottom of this. 
SSLVPN does something different than IPsec in terms of IPsec. So that could be the cause. 

Check the openvpn community as well, if you find some kind of hint there.