Una possibilità da non scartare è che il server c'abbia grossa grisi:
$ openssl s_client -connect
www.clienti.fcabank.it:443
CONNECTED(00000005)
write:errno=104
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 324 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
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Il sito era funzionante il 18 Nov 2019 21:07:22 GMT.
Leonardo
--
"You all presumably know why" :-) :-(