ok, i tried everything i found here and everywhere else... upgrading firmware, disabling firewall... messed up with my router configuration about 3 times... (and it was hard to get it up again). and here is what i got:
my adsl modem is a zyxel prestige 642r (router) working with PPPoE, i had all ports forwarded by SUA and still someway, my outgoing DCC SENDs were having the ports somewhat changed into sth near 10000-14000, no matter what...

analyzing that this could be a router funcion somewhat like a NAT, and as i didnt found a way to disable it, i started thinking to throw it out by the window, using it as a bed warmer or sth like that....

but than i though... HTF could my router detect mirc's DCC send command?? well.. it usually goes out by port 6667... so, if there is anything with syntax "DCC SEND filename ip port size" stuff, it could possibly detect it and change port name...
WHAT IF I WERE TO BE CONNECTED TO THE IRC SERVER AT PORT 7000 (for example?)

tadaaaaa
no more chaning ports... DCC RESUME WORKS!!! now the port that is sent, is the same that i receive in the DCC RESUME command

i hope this topic can help someone....

i have not tested other ports, as i spent the last 7 hours trying to fix this, maybe every port except 6667 willl work... if someone tests it, please post results