I have TP-Link MR3020 with OpenWrt 15.05.1 with all goodware installed and I've been running reverse SSH tunnel (OpenSSH on both sides) to Amazon EC2 Ubuntu 14.04 instance and pptpd server on router. Router is on firewall-ed network and I want to access that network regardless of our present VPN (which is really unstable).
I have tried to tunnel 1723 manually and do classic PPTP but I can't tunnel GRE protocol successfully and I get error 619 after timeout.
What are my other options here? Can I try single TCP port tunnel with OpenVPN? Can I setup OpenWrt as a client and then connect myself to VPS (will I be able to reach other devices on network or just those on MR3020?). I just need to hear from experts what is possible so I become "one" with the network and I shouldn't have issue implementing it.
PS I have chosen PPTP because of this great article that shows how OpenVPN has really poor performance on low-end routers https://justus.berlin/2016/02/performance-of-tunneling-methods-in-openwrt/