Hi @bruce
I have good news! My previous question in my last post led me to a solution for the "Luci no related RPC reply" issue encountered after updating to GL.iNet firmware 4.7. 
- Since I already had a backup of my settings prior to the update, I decided to reset the router with the 4.7 firmware to review the default configurations for both Nginx and uhttpd files using WinSCP method.
- I backed up the default configuration files for both Nginx and uhttpd.
- Next, I downgraded to a firmware version prior to 4.7 and restored my most recent settings backup, ensuring compatibility with that specific firmware version.
- I then adjusted the ports to their default values, using the backup files Nginx and uhttpd from my 4.7 firmware reset as a reference.
- After upgrading back to the latest 4.7 firmware, I was able to access Luci without encountering the error.
Please note that I cannot guarantee this method will work for others, but I wanted to share it in case it proves helpful. 
I recommend always creating a settings backup within Luci before making any changes. This precaution ensures that, if anything unexpected occurs, you can quickly restore your previous configuration without complications. 
Thank you for your support and Happy Thursday! 
PS: If you have time, I would greatly appreciate it if you could kindly review a post I made in November 2024. It may be possible to implement the stated example based on that discussion.