ssl certificate issue (ERR_SSL_PROTOCOL_ERROR) - ssl

Question

I have reissue my domain Certificate , then I've update certificate and key files for my servers it works only on one of them and get ERR_SSL_PROTOCOL_ERROR problem for others although all these servers use subdomains of the same domain . I have no idea where to look and how to trubleshooting this problem .
My question is : what would make ssl certificate work on one server and not work to another Although two servers use subdomains of same domain?
would you help me please ..
nginx configuration
server {
#listen 80;
#listen [::]:80;
# SSL configuration
#
ssl on;
ssl_certificate /etc/nginx/sites-available/ssl/mycert.crt;
ssl_certificate_key /etc/nginx/sites-available/ssl/mykey.key;
listen 443 ssl http2 default_server;
listen [::]:443 ssl http2 default_server;
#
# Note: You should disable gzip for SSL traffic.
# See: https://bugs.debian.org/773332
#
# Read up on ssl_ciphers to ensure a secure configuration.
# See: https://bugs.debian.org/765782
#
# Self signed certs generated by the ssl-cert package
# Don't use them in a production server!
#
# include snippets/snakeoil.conf;
root /var/www/html;
# Add index.php to the list if you are using PHP
index index.html index.htm index.nginx-debian.html index.php;
server_name _;
location / {
add_header 'Access-Control-Allow-Origin' '*';
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
add_header "Access-Control-Allow-Headers" "Authorization, Origin, X-
Requested-With, Content-Type, Accept";
try_files $uri $uri/ /index.php?$query_string;
}
server {
listen 80;
listen [::]:80 ;
server_name mydomain;
return 301 https://mydomain$request_uri;
}