Hi Il Phenomeno!!
I'm a big fan of you. I hope you will free yourself from the fear of being injured again and run like before. I see you on TV and i'm sure you have fully recovered all your potential.
Ok i'm with you
Let's talk about your post.
I'm also a newbie...
Here is my suggestions nevertheless
In your case i would check if my modem is perfectly supported by linux somewhere on the net archives.
What driver do you use?
Try to obtain the latest one for your material either open source or firmware
Because sometimes drivers present on distibutions packages are old versions
Make an investigation
If you found several drivers try them all to see what happen and tell me
See you Ciao