SSH and Screen Sharing Work on Remote OSX on Home Network but not SOCKS

I asked a similar question on superuser, but haven't gotten any responses. I'd like to be able to surf the web with my home IP address while abroad. I figured this would be easy to accomplish by allowing port forwarding on the home router to an old Mac laptop sitting at home (running OSX 10.9.5). After some fiddling with the Spectrum wifi router and allowing Remote Login and Screen Sharing under Sharing on the old Mac, I'm successfully able to ssh into the old laptop using the standard

user@remote

and even screen share by setting up local port forwarding using

-f user@remote -L 15900:127.0.0.1:5900 sleep 60

then running the Screen Sharing app. However, I'm unable to get a SOCKS tunnel to work. I use the standard

-D 5050 -C -N user@remote

, enter password, etc. All looks good. But when I try to point Firefox (correctly set up with manual SOCKSv5 proxy 127.0.0.1 on port 5050), Firefox just hangs. Any clues/ideas? Thank you very much for your help!