Please find attached the logs zip.
I am using 100 MBps internet provided by Elisa (Finland). I am not sure about the ISP.
Last night I installed DCS 1.5x. When I started it for the first time, a firewall warning was displayed about DCS. I allowed DCS to access internet and then I could successfully log in to the multiplayer.
However, when I manually allowed DCS 1.2x into the firewall, it did not work and my access to multiplayer was forbidden as before.
So to summarize, I can log in to DCS multiplayer using v1.5x, but not using v1.2x.
May be its the firewall which has blocked DCS 1.2 but I am not able to figure out how to solve it.
Thank you very much for all the help. Logs.zip