Sorry this will most definitely not work with your local IP address on an external DNS. That is not routable over the internet. I have a 192.168.10.20 IP address in my home network as well. You need to go to whatsmyip.com or ipchicken.com and get your external IP and put that in the DNS at your registrar. Most likely you will need a Dynamic DNS provider as your ISP probably gives you a dynamic public IP address that will change occasionally.
If you just want to resolve mydomain.tld INTERNALLY so you can use a mydomain.tld HTTPs certificate then you just need to add mydomain.tld to your INTERNAL DNS server pointing at your INTERNAL IP address for your server. Likely your router is set up as a DNS server but it just forward all requests to the external DNS which is why you just get sent to mydomain.tld instead of your internal server.
Sorry this will most definitely not work with your local IP address on an external DNS. That is not routable over the internet. I have a 192.168.10.20 IP address in my home network as well. You need to go to whatsmyip.com or ipchicken.com and get your external IP and put that in the DNS at your registrar. Most likely you will need a Dynamic DNS provider as your ISP probably gives you a dynamic public IP address that will change occasionally.
If you just want to resolve mydomain.tld INTERNALLY so you can use a mydomain.tld HTTPs certificate then you just need to add mydomain.tld to your INTERNAL DNS server pointing at your INTERNAL IP address for your server. Likely your router is set up as a DNS server but it just forward all requests to the external DNS which is why you just get sent to mydomain.tld instead of your internal server.