Status is now:

- In mysql I see the correct umlauts with phpmyadmin

- Database is utf8_general_ci

- if I read mysql and send it to a website it looks like �

- If I change the � in the browser to the correct umlaut and send it to Mysql and read it again from DB I got the correct Umlaut on the website but in mysql with phpmyadmin it looks like ü

- I have also tried to open mysql in perl with
mysql_enable_utf8 => 1
or
$dbh->{'mysql_enable_utf8'} = 1
or
$dbh->do(SET NAMES 'utf-8')
without any change.

- Websites are set to charset=utf8

- httpd.conf is set to utf8

- If I read a regulare text-file (Umlauts shown as umlauts) in the website and the umlauts changes to �

- if I change the umlauts in the textfile to ü the umlauts on the webpage are correct.

System is Centos7.

I have no idea how I can leave this hell. What can I do now?

Vagabundo

Perhaps there is a conflict between the locale settings on the computers in question.

What is the output of the locale command on the computers in question (I'm hoping that you have shell access to the server)?

# locale
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

I'm no expert in this and certainly am not qualified to offer a solution, but I think en_US.UTF-8 might have difficulty with umlauts.

A web search led me to these articles, which might help:

https://en.wikipedia.org/wiki/UTF-8#Codepage_layout

https://www.madboa.com/geek/utf8/

https://help.ubuntu.com/community/Locale

I hope someone who has experience dealing with this issue will see this and suggest a fix.