Help with Zyxel router

hi,

I have this problem in which the WAN port in my Zyxel 324 router has
some kind of incompatibility with the ethernet port on my thompson cable
modem.

What happens is that when I connect these two together they don't seem
to see each other (the connection leds don't light up on either device),
as if there was no cable inserted.

The funny thing is, if I just leave them alone for a few hours, they
eventualy seem to get along, and everything works fine... until the next
power failure. I've tried with cross-over and straight through cables,
same result.

Suspecting this had something to do with the auto-sensing ability on
both devices,(10 or 100, straight or cross-over), I tried placing a hub
in the middle with only these guys in, and guess what, the leds light up
instantly, I get an IP address from my provider and everything works the
way it should... except for that hub in
between and an extra power supply.

My question is, is there any way to force the Zyxel WAN port to be 10 or
100Mbit,not leting it auto-sense anything? I've gone through all the
configuration menus and found nothing about this....

regards
alexandre salvador