IPFS with CGNAT

Hello,
I am a beginner with IPFS. I tried to share a file using IPFS from my desktop computer. It works in the local network but not outside of it. I suspect it is because my network is behind a CGNAT but I am not sure.
My OS is Debian Buster.
I installed IPFS following this: http://docs.ipfs.io.ipns.localhost:8080/how-to/command-line-quick-start/#prerequisites
I added the IPFS companion module to Firefox and when I launch the ipfs daemon I see some peers connected.
Then I tried to add a file to IPFS with " ipfs add ‘my_file’ ". If I try to access my file writing " https://gateway.ipfs.io/ipfs/‘cid_of_my_file’ " in Firefox, I get my file only when I do it from the local network.
Could someone help me to identify the issue and if possible to solve it?
Best regards
Gilles