Remote access on multiple routers

I have Xiaomi router AX1800 that servers as my local lan router. All my devices and home assistant server running debian are connected on it. This router is also main mesh wifi router connected to another mesh node.
AX1800 router is connected via powerlink adapter to cisco rv320 router. Xiaomi is connected from wan port to cisco lan port. On cisco router I have two wan ports connecting two lte routers - FritzBox 6890 lte and Huawei B535 lte router connected to two wan ports.
Now, the problem is how to set up remote access to home assistant.
I use dynu dns addon to get my certificate. I got certificate very simple. I created my ddns domain, forwared port 80 and 443 on my xiaomi, cisco and fritzbox router. Ddns ip address is updated regularly and I propagated my ddns domain but I cant connect from outside. On dynu control panel I tried to ping my ip and my domain but all pings were rejected. I tried to disable firewall on my lte routers, but nothing changed.
I’m a bit stuck here because I’m not sure were the problem is. In my configuration.yaml i have

use_x_forwarded_for: true
    - ::1```

I tried to play aroung with nginx proxy and nignx ssl but no luck. I believe that problems lies somewere in cisco configuration but I’m not sure.
Can someone help me to find a way how to access my home assistant from outside?

EDIT: I think I found a problem. So I will answer to myself. My isp is using so called grey ip address. That is the reason I cant set up ddns.