Question : VPN between Draytek and Zyxel continuously dropping every few seconds

I have just configured a site-to-site VPN between a Draytek 2800 which dials out to a Zyxel 650 (it's a few years old now) but the connection drops out constantly, sometimes after 5 seconds and sometimes after a minute but never longer than that.
Are there any obvious things that I have overlooked at either end that I should check out, or how much more info do you need to be of assistance?

Some basic settings:
Draytek, dialing out: VPN is set to 'always on,' 'ping to keep alive' is enabled and it pings the public IP of the Zyxel at the other end.
IPSec security is set to High, 3DES with Authentication.
WAN IP: 0.0.0.0
Remote gateway: 0.0.0.0
Remote network IP: 192.168.1.0
Remote network mask: 255.255.255.0
RIP disabled
Other option in Draytek is " For NAT operation, treat remote sub-net as" - Private IP
"Change default route to this VPN tunnel" - not ticked.
Keep-alive is not enabled.


At Zyxel (host) end:
IPSec key mode: IKE
Negotiation: Main
Encap.: Tunnel
Keep alive is enabled.

Help would be appreciated.

Answer : VPN between Draytek and Zyxel continuously dropping every few seconds

Good luck with it.
Surprised you would loose the Internet at 1300. You should be able to lower it well below that without an issue. Dial up connections use 576, though I have never tried going that low.