How to use Rstudio Server without firewall



Good day,
I am not an expert but I could install Rstudio Server on our cluster.
I follow the procedure and I enabled the firewall and I open the port 8787 and 80.
The problem now, my nodes do not communicate with my server.
I can have the services back if I disabled the firewall, but then Rstudio Server will not work with 8787.

Is there a way to have my master/nodes working and Rstudio Server on port 8787 without using the firewall?
(The port 80 is need for my master. It display the cluster status)