Connection to github.com closed by remote host

Problem is exactly as reported in - https://unix.stackexchange.com/questions/237158/ - https://unix.stackexchange.com/questions/331641/ But it is ***not*** the "ssh_exchange_identification:" error, i.e., it's different than the https://unix.stackexchange.com/questions/19378/ one. I'm getting it while doing ssh -T:

$ ssh -T git@github.com
Connection to github.com closed by remote host.

The following message is generated when using ssh -vvv

debug2: channel 0: request shell confirm 1
debug3: send packet: type 98
debug2: channel_input_open_confirmation: channel 0: callback done
debug2: channel 0: open confirm rwindow 32000 rmax 35000
debug3: send packet: type 1
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
  #0 client-session (t4 r43 i0/0 o0/0 fd 5/6 cc -1)
Connection to github.com closed by remote host.

I've put the the full log (and diff with normal) to: https://www.diffchecker.com/LF2ZEb8j For ssh -vvT git@github.com, I've put the the log diff to: https://www.diffchecker.com/WjmA7P0c from which there isn't much revealing. Once again, the above problem is from (connecting from) my remote server, of version 1:7.6p1-4ubuntu0.7, which has been working for years, but have now broken for a few weeks. Testing/connecting from my home machine (ver: 1:8.4p1-5) always OK. Comments? Is it that my openssh-client 1:7.6p1-4ubuntu0.7 is too old for github.com? $ apt-cache policy openssh-client openssh-client: Installed: 1:7.6p1-4ubuntu0.7 Candidate: 1:7.6p1-4ubuntu0.7 Version table: *** 1:7.6p1-4ubuntu0.7 500 500 http://azure.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages 100 /var/lib/dpkg/status 1:7.6p1-4ubuntu0.5 500 500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages 1:7.6p1-4 500 500 http://azure.archive.ubuntu.com/ubuntu bionic/main amd64 Packages