Hello,
I have stacked at router setup. Lost time and money. any help well come! Thanks.
Im not an experienced user. Trying to search info and guides online but not understanding most of it 
Problem:
I am trying to set up a wifi captive portal with mikrotik router. I have purchased a software for this. I set up everything which was easy until i get the setting part where i got connection problem between router and web server because of my networks Nat problem.
What i have to setup was quite easy : Get Ipcloud Dddns address then in the web server settings paste ddns address and port.
But my mikrotik router having problems getting DDns address. Even when gets not working with the server. Router is behind another Router Tplink home router which is connected to ISP. And when i check TPlink routers wan settings i see another network.
I asked developer to help. He helped me and set up in my router a vpn(l2tp tunnel) xxx.hisvpn.com
He set up same vpn on web server ddns address and everthing worked fine.
https://i.imgur.com/1CvHzAO.jpg
But the problem is this vpn not stable. I think vpn is on his computer and daily shutting off. He is not responsive either not answering my questions. I think he has CHR installed olso on vps.
May be anyone can help me?
I have setup on a vps l2tp vpn and don’t know next step. Or may be there is other easier way?
Thanks.