Resolved Incorrect SSL certificate on IPv4, but OK on IPv6

[David - ECA]

Server operating system version

Ubuntu 24.04

Plesk version and microupdate number

18.0.63 Update #4

Hello everyone,
I'm contacting you because I'm experiencing a problem on my Plesk: Following a change of IPv4 address on my server (the IPv6 addresses haven't changed), for all the subscriptions affected by this IP change, the SSL certificate (Let's Encrypt) works correctly on IPv6, but the default certificate is used for IPv4, instead of the certificate defined on the website.
I've tried recreating the certificate, but it makes no difference.
Does anyone have any idea what is causing the problem?
Thank you in advance for your feedback.
Best regards, David

 

[David - ECA]

Hello everyone,

After talking to Plesk support (very reactive! Thanks to them!), we found the solution!

The problem came from the IP change:
The new IP is a floating IP (Openstack) linked to a private IP in NAT 1:1 (it was the first time I had this type of configuration, I had always worked with public IPs directly, until now).

And in Plesk, don't use the public IP directly! You have to configure the private IP to indicate the correct public IP (in “Tools & settings” => “IP addresses”), then assign the private IP to the relevant subscriptions, not the public IP!

Hope this helps!