Nat loopback issue

Configuration
1

Hello guys,

I need your help please. i changed my internet provider, and since i can’t play audio on my Google Home,

Also i can’t log to HA from the application when i’m connected to Wifi :

Cellular network:
mobile phone access to https://my_duckdns.org:8123 == ok

Local network
PC access to https://my_duckdns.org:8123 == fail
PC access to https://ip_address:8123 == ok
mobile phone access to https://ip_address:8123 == fail
mobile phone access to https://my_duckdns.org:8123 == fail

I use : Home Assistant 2021.7.4 on Synology

here my network configuration : Provider router <===> My Xiaomi Router <===> Synology

On the provider router i already set up a port forward 8123 to Xiaomi router to synology

Here is my logs :

Failed to cast media None. Please make sure the URL is: Reachable from the cast device and either a publicly resolvable hostname or an IP address
11:05:28 PM – (ERROR) Google Cast - message first occurred at 10:55:07 PM and shows up 5 times

Thank for your help

2

Can you remove the provided router and just use your Xiaomi Router, assuming it Supports NAT Loopback?

i.e. does your ISP provide the information required for BYO (bring your own) routers?

3

Unfortunately i can’t, and i don’t have the admin access to it. i need to ask them to forward port.

Yes Xiaomi router support it. it worked before when i have the old ISP Provider + my Router Xiaomi