Dear Mars Comet,
Although they aren't supposed to (at least in the US), some ISPs block or throttle down certain ports to discourage p2p users. (See
http://www.amule.org/wiki/index.php/Extended_client_UDP_port).
If this is the cause of your trouble, you can avoid such ISP interference by selecting port numbers other than the defaults. (I use 5992 and 5995, for example.) They can be changed in Preferences --> Connection.
Whatever numbers you choose, be sure they are not reserved for other connections you currently use or may wish to use in the future. (
http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers)
And, of course, don't forget to change your firewall and router settings to accomodate your new settings.
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To tinkerbellarulez:
Yes, eMule and aMule use the same default ports. Limewire, FrostWire and Bearshare use different ones as their defaults: 6346 and 6347. You might wish to try the same suggestion I offered to Mars Comet above for both applications.
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To both:
Other than the reason I mentioned at the beginning, I can't come up with any other causes, unless there's something you don't know about (such as your ISP putting you behind a proxy server). It sounds as though you have performed all the necessary tests and tweaks to get aMule up and running with a High ID.
Best of luck.