I use simple Lets Encrypt certificate. But my website shows me in the cert properties some problem.
Here it is:
Connection - obsolete connection settings
The connection to this site is encrypted and authenticated using TLS 1.2, ECDHE_RSA with P-256, and AES_256_CBC with HMAC-SHA1.
AES_256_CBC is obsolete. Enable an AES-GCM-based cipher suite.
I am not sure that this is certificate problem.
Hope anybody can tell me how to fix this.
It looks like you are using IIS, to configure the set of SSL/TLS cipher suites your servers will support requires settings several registry keys. The easiest way to do this is using the IIS Crypt tool: Nartac Software - IIS Crypto -
Select Best Practices to begin with, then unselect any cipher suites you specifically want to remove, apply and restart the server. There is also a 'Strict' template you can apply but you should proceed with caution as deselecting the wrong cipher can disable your ability to use RDP etc depending on your OS version.