(1) Just in case double check each IP address and port. I've seen similar problems due to common typos. (2) Did you set everything up by yourself? If not then maybe the setup is not what you think. Can it be your interactive login to the SSH server somehow results in
ssh yet_another_server automatically from there? If this was the case, your tunnel would end on the first server (and imagine it cannot reach the web servers), while your curl 10.100.1.50:80 only proves you can reach the web server from the ultimate SSH server.