@Clive_A 

Thanks for your quick replay.

It's a funny thing that there is VPN router with capacity of 110 OpenVPN tunnel at the same time, and If I would like to connect 110 vpn user I have to connect 10 wan connection to the router. And after that where can I put the lan segments :)

Another thing: there isnt any reference for this limitation in the router's users guide. 

But ok, now I share my today's experience for those who have the same problem, I found a solution which works so here it is.

SOLUTION 

STEP 1. Create an OPEN VPN SERVER with settings what you want to udp 1194 port. Create 10 users, and assaign to that.

STEP 2. Create another OPEN VPN SERVER to UDP 1195. Be sure to change the ip address pool for the remote users. Create another 10 users, and assaign to that.

Repeat steps till you cover all your desired vpn client. Attention to increase the port number in every step. 1194, 95,96....and so on.

Suggestion for IP pool: 

I name the VPN servers as follow: OPEN VPN 1194/20. For that I use the following pool: 192.168.20.1/24

And than OPEN VPN 1195/30 -> 192.168.30.1/24

And so on...

It works for us with 34 users, and we have only 1 internet connection. (600/30 Mbit)

Interesting thing for L2TP: 

Users with unstable l2tp connection can connect to openvpn without any issue, and the connection is perfect. They use the openvpn about 4 hours without any brake. When we try it again to L2TP it's unstable. It's not a problem now, because we use openvpn. But I thinks there are some bugs in the router. 

Another interesting thing for PPTP :)

We setup server for PPTP, but we can not connect to it. When we try it, the process reach for that point when check username and password, and it stucked.

After we restart the router, we can connect. But 1 days later the problem come again, and can not connect. 

So my conclusion is: FORGET L2TP, and PPTP, use OPENVPN. And follow the instructions I mentioned.