Idem sous windows 10, sur un PC qui accepte le certificat :
>openssl s_client -connect www.arcep.fr:443 -status -servername www.arcep.fr
Loading 'screen' into random state - done
CONNECTED(000001EC)
OCSP response: no response sent
depth=0 businessCategory = Government Entity, serialNumber = 110 000 353, 1.3.6.1.4.1.311.60.2.1.3 = FR, C = FR, ST = ile de france, L = paris, street = 7 square Max Hymans, OU = *, O = AUTORITE REGUL COMM ELECTRO POSTES, CN = vpn.arcep.fr
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 businessCategory = Government Entity, serialNumber = 110 000 353, 1.3.6.1.4.1.311.60.2.1.3 = FR, C = FR, ST = ile de france, L = paris, street = 7 square Max Hymans, OU = *, O = AUTORITE REGUL COMM ELECTRO POSTES, CN = vpn.arcep.fr
verify error:num=27:certificate not trusted
verify return:1
depth=0 businessCategory = Government Entity, serialNumber = 110 000 353, 1.3.6.1.4.1.311.60.2.1.3 = FR, C = FR, ST = ile de france, L = paris, street = 7 square Max Hymans, OU = *, O = AUTORITE REGUL COMM ELECTRO POSTES, CN = vpn.arcep.fr
verify error:num=21:unable to verify the first certificate
verify return:1
---
Certificate chain
0 s:/businessCategory=Government Entity/serialNumber=110 000 353/1.3.6.1.4.1.311.60.2.1.3=FR/C=FR/ST=ile de france/L=paris/street=7 square Max Hymans/OU=*/O=AUTORITE REGUL COMM ELECTRO POSTES/CN=vpn.arcep.fr
i:/C=BE/O=GlobalSign nv-sa/CN=GlobalSign Extended Validation CA - SHA256 - G3
....
Je n'ai mis que le début.