IDRAC8 unable to use html5 console after update

Hi,

I've spent some days browsing similar problems on various forum but did not find the solution, may be because I'm not familar with certificates!
On a power-edge R730 I've updated firmwares, BIOS and IDRAC.
IDRAC from 2.21.21.21
-> 2.40.40.40
-> 2.60.60.60
-> 2.75.100.75

-> 2.83.83.83

-> 2.86.86.86 (latest)
I solved the "400 ERROR" with https://www.dell.com/community/en/conversations/poweredge-hardware-general/idrac-9-version-6100000-400-bad-request-error/647fa22ef4ccf8a8de79c7a0 instructions, so the web interface is OK now.

But launching the HTML5 console fails with "Expiration de la session d'attente de vérification du certificat.
Toutes les connexions seront arrêtées." message (in english: Session waiting for certificate verification timed out.
All connections will be terminated.) after a timeout. And I'm stuck with this.

My browser is Firefox 115.14.0esr in AlmaLinux8 OS.

Thanks for your help.

Patrick