http/2 server push ssl error

I installed http/2 server push plugin on my wordpress site. Since then I get this error code and can not access my website anymore (also no backend access)
This can’t be reached
The web page at https://v2.miteinander-reden.net/ might be temporarily down or it may have moved permanently to a new web address.
ERR_SSL_UNRECOGNIZED_NAME_ALERT

How can I get rid of this?
Is deleting the plugin an option?

Thank you,
Johannes

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