Networking

I need to understand Network issue which i haven't been able to figure out. I have NAS set up for home network which i'm not able to access from outside of my network. My router is behind 3 different routers. I do understand port forwarding however i do not have access to # 2 router where i can set port forwarding rules. How can i accomplish it without port forwarding?

Is there any IP segment issue?

1-Modem

2- Roter (Public IP - 172.34.56.23 (not real - just for understanding) )

3- Wifi Repeater ( NAT )

4 - Wifi Repeater ( 192.168.1.234 (NAT from # 3) )

5 - My Router ( 10.20.10.20 Gateway ) this is also configured for NAT.