Why Ansible won't connect to Zyxel Zywall?

Question

ZyXEL

Hello.
Trying to set up Ansible to manage Zyxel Zywall.
I took this article as a basis networkop.github.io/blog/2015/06/24/ansible-intro I
set everything up.
I'm trying to run a command

$ ansible zywall -u admin -m raw -a  ping -vvvv
Using /home/lebedev/zywall/ansible.cfg as config file
Loaded callback minimal of type stdout, v2.0
<192.168.91.254> ESTABLISH CONNECTION FOR USER: admin on PORT 22 TO 192.168.91.254
<192.168.92.254> ESTABLISH CONNECTION FOR USER: admin on PORT 22 TO 192.168.92.254
<192.168.92.254> EXEC ping
<192.168.91.254> EXEC ping

And silence.
When connecting via ssh to Zywall (USG series) gives the following

$ ssh [email protected]
Password: 
Bad terminal type: "xterm". Will assume vt100.
Router>

Where to dig?