Finally! I have found the problem.
I use Cloudflare to manage my DNS entries, and I have checked the default "proxied" status, which hide my public IP address.
But in this case, I can't access any of my personal service behind my router. Not only Traefik, but even the other hardware like nas on non common ports.
It only gives me the "The page is not correctly redirected" error.
I have modified the DNS entries from "proxied" to "DNS only" and it is working as before.
[Edit] Ok, it is obvious after thinking it. As it is proxied, the requests arrives first to Cloudflare, for the DNS resolution, and from Cloudflare to my router/firewall. Cloudflare is not in my country of residence. As I block any other country in my firewall, I have blocked Cloudflare. And as the requests are proxied, thy comes from Cloudflare...
[Edit 2] Not so obvious, my 80/TCP (HTTP) and 443/TCP (HTTPS) was allowed from anywhere, I have only blocked other ports, so it should not be blocked by my firewall.
I tried without blocking anything, with Cloudflare proxied DNS, I always get the "The page is not correctly redirected" error. In DNS only mode, it works immediately.
[Edit 3] It seems to work with proxied DNS when replacing the SSL/TLS encryption mode from "Flexible" to "Full (strict)".