I have a Debian 9 server that is running Solr 7.3.
I have upgraded to Debian 11, Solr is still fine.
Now I'm trying to install Solr 9 alongside Solr 7.3, to have both versions running in the same time. I followed the official guide.
bash ./install_solr_service.sh solr-9.0.0.tgz -i /opt -d /var/solr9 -u solr -s solr9 -p 8984
the installation seems to work fine systemctl status solr9.service says
● solr9.service - LSB: Controls Apache Solr as a Service
     Loaded: loaded (/etc/init.d/solr9; generated)
     Active: active (exited) since Mon 2022-11-14 12:43:13 UTC; 4min 47s ago
       Docs: man:systemd-sysv-generator(8)
    Process: 6781 ExecStart=/etc/init.d/solr9 start (code=exited, status=0/SUCCESS)
Nov 14 12:43:07 xxx systemd[1]: Starting LSB: Controls Apache Solr as a Service...
Nov 14 12:43:13 xxx solr9[6835]: Started Solr server on port 8984 (pid=6830). Happy searching!
Nov 14 12:43:13 xxx systemd[1]: Started LSB: Controls Apache Solr as a Service.
but I can't reach Solr9 panel from the browser.
I have checked iptables --list and settings for port 8983 (where is running Solr 7.3) are the same of port 8984 (where is running Solr 9).
lsof -i | grep 8983 says
java    5622        solr   37u  IPv6 117480      0t0  TCP *:8983 (LISTEN)
but lsof -i | grep 8984 says
java    6830        solr  136u  IPv6 134506      0t0  TCP localhost.localdomain:8984