I experienced two machine unable to connect via ssh or curl. Its hang or connection close before authentication. But Finally I found that they both has the same issue. How I solved it?

For ssh issue I saw that if I specify chipher algorithmn then problem got solved. So I ended up with following solution - 

I add  created a config file in ~/.ssh directory then write following line - 

# ~/.ssh/config
Host *
KexAlgorithms ecdh-sha2-nistp521

But I faced the curl not working. It was my another problem. I finally saw that if I lower MTU value for my network interface then both problem got solve. We do not need to provide the ssh config solution.

By following command you can change MTU value. My MTU value was 1500 and I lower it to 1200

sudo ip li set mtu 1200 dev wlp3s0

Or

sudo ifconfig wlp3s0 mtu 1200

There are many more bug in openssh package. So whenever you face a problem check bug list.