Usg vpn site to site UP but not working

Roma123

I have a vpn site to site with usg110 and usg 210. Vpn bring UP but not working any connection. I follow some guide on internet. In these guide there aren't firewall rule or nat rule. I think that this is a problem.

parnassus

Following some guides found on Internet is probably not a very good starting point: why not simply start with official ZyXEL KB Articles as foundation for your configurations? it's the path I personally prefer.

As example:

• ZyXEL IPSec VPN Site to Site (Static IP Public addresses) KB Article
• ZyXEL VTI VPN Site to Site (Static IP Public addresses) KB Article <-- if you have both USG with 4.20 or newer you can use VTI instead of more common IPSec approach (useful if you are planning in near/far future to perform VPN tunnel balancing over two WAN interfaces on each side).

I used the ZyXEL VTI approach without any issue between USG110, USG40 and USG60 since 4.20 firmware release.

Zyxel_Charlie

@parnassus, Thanks for your sharing.

Hello Roma123,
I want to confirm that is your topology like  
USG110--(VPN connection)---internet---(VPN connection)--USG210?
You can follow the configuration which parnassus shared, and here is the similar example of VPN from FAQ as your reference.
https://businessforum.zyxel.com/discussion/551/an-example-of-site-to-site-vpn#latest 
Charlie