I have the same error!!!
exactly as you describe it.
I even thought my isp was blocking my ports because of the high trafic I've been changing the ports amule uses I whent from 4662 to 26500 to 60000, whenever I changed ports and restarted amule I got my high ID back, but after 1 or 2 hours bang very low dls (very very low like 3 and 4 KB) again, and with a simple reconect to a server I could see that I now had lowID AGAIN.
What I've now learned is that it isnt a port thing cuz whenever I have the problem I just restart amule with the same port that was giving me lowID and I have HighId back.
Can someone plz point uz where to put this thread to have more visibility, cuz this is a MAJOR bug.
tnx
g.
ps I have an ImacG5 20" MacOSX 10.4.1
EDIT: I an sure I have my router (nat and firewall) configured, Its not a server thing cuz I've tryed to conect to a lot of diferent servers, and its not my isp who is blocking my ports cuz I've tryed a lot of ports.