GnuPG does not communicate with key servers

I happen to find I cannot upload my key to ANY key server. The problem is odd that of two gpg branch, 1.4.23 works, but 2.2.27 (the last version on WinXP) do not work:

1.4.23>gpg -vvv --keyserver keyserver.ubuntu.com --search-keys 0x57548DCD
gpg: using character set `utf-8'
gpg: searching for "0x57548DCD" from hkp server keyserver.ubuntu.com
(1)     Werner Koch (gnupg sig) <dd9jn@gnu.org>
          1024 bit DSA key 57548DCD, created: 1998-07-07
Keys 1-1 of 1 for "0x57548DCD".  Enter number(s), N)ext, or Q)uit > n
Enter number(s), N)ext, or Q)uit > q

2.2.27>gpg -vvv --keyserver keyserver.ubuntu.com --search-keys 0x57548DCD
gpg: using character set 'utf-8'
gpg: error searching keyserver: Unknown error
gpg: keyserver search failed: Unknown error

And I am always using 2.2.27, because Enigmail demands gnupg 2.0 branch. I recall I had updated my key using v2.2.27 before.

It gets even odder when I use wireshark and see that gpg2 does not initiate any connection to keyserver.