I am not a Shareaza user but when it comes to connection problems, it is generally a firewalling problem. Things to check:
1. Make sure Shareaza has an exception in your firewall.
2. (i) Your situation may require port forwarding. Find the port(s) Shareaza is using and set up port forward rules. The alternative is to instead set up Port Triggers which is the same thing except less demanding on the setup process. The very first step for port forwarding should always be to set up a Static address on your local LAN network https://portforward.com/networking/staticip.htm (only needs to be done once though.) Note: I would recommend using a relatively high internal address number.
(ii) Log-in to your router and set up port forwarding. Find your brand and then model of router https://portforward.com/router.htm You will need to port forward both TCP and UDP for the same ports. You can either set up separate rules for each or there's usually the option to choose 'both' UDP and TCP. Use the port Shareaza is using. Alternatively you can set up a custom port but remember to also change the port(s) Shareaza is using. What custom ports you can use, see http://www.gnutellaforums.com/tips-t...formation.html though you can choose most ports above 10000 but below 65535.

Shareaza has web cache support so it should still be able to find hosts for each of the networks. In theory the program should only need to find a single active host to be able to connect. That host will pass on bonus hosts for Shareaza to try to connect to.