I have the same problem with my zyxel P600. When the transfer rate becomes too high it drops the line and immediately reconnects. Even weirder is that it drops the line when smtp transfers exceed 2MB.It cant be something to do with the line because when I replace the Zyxel with my older Netgear DG834 everything works properly at full speed.I think there is something wrong with the zyxel and unless I get to the bottom of this it will end up in the bin.
proteuss, are you an Earthlink customer? If not let us know and we can move your post to the correct forum for some help.
No, I am not an Earthling customer. My apologies if I butted in.I am very frustrated with this crappy modem. I bought it for its bandwidth management capability but it seems to be worst that the old cheapo NetGear.
No apologies needed. It sounds like you could use some help so let's try our Zyxel Forum.Good luck.