Remote access can be tricky depending on your home network setup, router configuration and ISP. However if you cannot even access the Plex forum / web app, this means there might be something else going on with the network configuration of those clients (laptop, mobile phone).
- As for remote access troubleshooting → The Basics of Remote Access Troubleshooting
- As for the client network access… are those devices connecting to the network through some VPN or other security apps/tools/components? Any special DNS configuration on those devices?