Duckdns Remote control Port forwarding

Hello!
A few days ago the ISP provider gaves me a external ip and ability to forward ports, So i did it, I forwared a port 8123. After this i installed a duckdns addon and this is my config:

{
  "lets_encrypt": {
    "accept_terms": true,
    "certfile": "fullchain.pem",
    "keyfile": "privkey.pem"
  },
  "token": "xxxxxxxxxxxxxxxxxxxxxxxxxxxx",
  "domains": [
    "nameofdomain.duckdns.org"
  ],
  "seconds": 300
}

In configuration.yaml I got:

http:
  base_url: https://nameofdomain.duckdns.org:8123
  ssl_certificate: /ssl/fullchain.pem
  ssl_key: /ssl/privkey.pem

When i connect to hassio by my android phone not connected to local wifi everything is working fine. The problem is when i use the pc connected to the same lan/wifi. Site is not loading at all. When i connect to local ip https://192.168.100.12:8123 it is working. I could use this kind of adress on my pc but i need to configure another addons webui addresses aswell, so it is a problem. If i define it like 192.168… it wont work when i connect by adress https://mydomain.duckds.org:8123. What i have to do? How to make it work by domain name on pc connected to lan aswell?