Hi Batmanuel.........
No solution right now for you, but at least a little piece of good news.....
If you are using a 'legal' 56k modem and you are managing an average 50666bps, you should be a very happy camper!
That is in fact very good average performance.
Your problem is very possibly in your setups for your dial-up connection and maintaining that connection and re-connecting manually or automatically.
Do you experience frequent disconnects when using other programs, especiallly Outlook Express? And, if using OE, do you receive a message saying that the file size is too great if/when you try to send an e-mail with an attachment which is over 1.5MB ???
Also, please remember to always include the basic information about your system whenever you post for help -
Operating System
Processor type
Memory
Internet Service Provider connection type
Gnutella client version
It will help others help you in fewer posts and a shorter time....
We can only guess you are using Windows because of the mention of your
winmodem 
And, don't despair.... you'll get it working!