You may know this but just in case:
Using a web browser requires the Web Server feature.
Using the RSOIP in Client mode or the Free Client requires the Remote Scanner Over IP feature.
If you are running both the Remote Scanner Over IP feature and Web Server feature then use different port numbers for each.
If the RSOIP is using port 5000 then the Web server can use 5001 or whatever port # you want to use.
In the router Port Forwarding section, setup two rules. One for the RSOIP port 5000 and another for the Web Server port 5001.
Port 5000 and 5001 are used just for examples. You can use any port numbers you want.
Use
https://canyouseeme.og/ to test port 5000 and 5001
Server Not Responding Code 9 messages means that the near end can't communicate with the far end for some reason. The TCP protocol doesn't provide where the problem is. To troubleshoot that, try connecting with other RSOIP servers, if the problem goes away then the problem is on the server side. If it's intermittent then it could be cables, connectors, nic cards, etc.
{edit} I'm not familiar with the Bryx cell phone app. I looked it up and that uses the Bryx Fire Station Alerting System.
So It's not compatible with the Web Server or RSOIP server features