Problems updating (M)Elpa packages

[Angelo Graziosi]

The following issue occurs on two machines WiFi connected, one with W10 Home 64 
and one with macOS (10.13). I do:

  Options - Manage Emacs packages

a 'Network Security Manager' buffer shows up, containing 'Certificate 
information', saying that 

'TLS connection to elpa.gnu.org:443 is insicure for the following reasons:

safe renegotiation is not supported, connection not protected...'

and ask to accept the connection

Always
no
session only
...

I do 'session only'.

On the W10 Home machine, 3 years old, this work but on macOS machine, 8 years 
old, it fails:

'error in process sentinel: Error retrieving: 
https://elpa.gnu.org/packages/archive-contents (error connection-failed 
"connect" :host "elpa.gnu.org" :service 443)'

It is the first time I see this after years using (M)Elpa.

The builds regard master of about September 03.

On another machine, dual boot W10 Pro 64 and Gnu/Linux Mint 64, same master 
builds, ethernet connected, this DOES NOT occur.

Angelo