Hello @oaz,
About access to admin dashboard: https://i.postimg.cc/3N4VvSDS/image.png
Please check the error logs on your server for a more specific error message, which may give a clue to why this is happening on your website/server. If you need help locating them, ask your hosting provider to help you with that.
If you cannot find error logs or if you don’t find any helpful info in the error logs, try Enabling debugging
Meanwhile, try:
– manually resetting your plugins (no Dashboard access required). If that resolves the issue, reactivate each one individually until you find the cause.
– If that does not resolve the issue, access your server via SFTP or FTP, or a file manager in your hosting account’s control panel, navigate to /wp-content/themes/ and rename the directory of your currently active theme. This will force the default theme to activate and hopefully rule-out a theme-specific issue (theme functions can interfere like plugins).
About Internal Server Error:
Could you please send a link or screenshot from your chosen hosting plan? I’m curious to know about your hosting.
In the shared hosting, obviously, all resources are fine but shared with 2 or 3 or until 20 users. in an optimistic situation you the only using it, but at this time not, Let me explain how.
So guess what happened, you haven’t an issue from MEC others plugin or theme or WordPress, it just no happened.
This is shared host and when the traffic on the server is very low and resources are open for you, but unfortunately, it is temporarily, until to increase traffic and use more resources on your server.
I know you set the very well configuration and I know you can see the perfect configuration on your server, but it is shared with more than 10 other users that host server knows it.
You can try it, ask your question in other host provider sites to know more about it.
If there is anything else we can help you with please share.
Best Regards