It worked for me. you can use these steps:

apt install php-mbstring bind9-utils

add 4445 TCP in firewall

wget -O - http://download.fop2.com/install_fop2.sh | bash
chown -R asterisk:asterisk /var/www/html/fop2/
cd /usr/local/fop2
chown asterisk:asterisk .
bash /usr/local/fop2/setSSL.sh
systemctl restart fop2

But the service keeps restarting

Good Morning,
I have installed a WebRTC Browser Phone on FOP2 on Issabel Server
I have lets encrypt cert
I have followed this guide http://www.fop2.com/docs/webrtc_guide.php and now when i use fop2 it register the extension and can make calls and receive but there is no audio in both ways, Speaker and mic from the WebRTC Side, and when checking the call record i can hear the sound of the softphone
the calls ends in 30 secs
I am on Issabel with Asterisk 11 and fop2 latest version
also i noticed that the browser show me Not Secure connection when i go to https://mydomain.com/fop2/
while it show me Connection is secure for https://mydomain.com/...
also i found iceConnectionDisconnected in console
what should i do to have the audio working form the webrtc side on both ways?