After adding ssl i can't visite my wordpress site. It says This site can’t provide a secure connection and ERR_SSL_PROTOCOL_ERROR.
This is a very general error and it's hard to give you an accurate advise. As the first stop, I would suggest using one of the online SSL checkers. They provide different levels of test so they can be fast (a few seconds) or slow (up to several minutes).
https://www.thesslstore.com/ssltools/ssl-checker.php - cert installation test (fast)
https://www.ssllabs.com/ssltest/ - thorough security analysis (slow)
https://gf.dev/tls-scanner - security analysis (slow)
https://www.immuniweb.com/ssl/ - security analysis (slow)
https://keychest.net - this one requires a free registration, baseline and config checks (fast)
I've worked around (not only) SSL security for over 20 years in enterprises and startups.
I am now running an HTTPS expiry management service KeyChest.net