@tintin_uk Probabably an etehernet cable issue. Use another cable (CAT5E/6) for connecting to AX50. See this troubleshooting thread for details.

@EHM Try another browser or incognito/private browser window to see if any difference. If still don't see that option you may try resetting the router to factory defaults and re-configure from...

@EHM If the ping reply is OK then my-dnsname.tplinkdns.com binding is successful. How to login with local admin account:

@EHM Have you tried to ping my-dnsname.tplinkdns.com URL and see if the reply is from your router's WAN IP address (your public IP address) ? If it is, then the registration was successful. Logout...

@TKwsNi Well that's a perfect timing to test that - you can go ahead and upgrade your C50 FW to the latest FW release I posted in my previous post. Here's how to upgrade the router's FW (case 1).

@EHM Make sure that you're with the latest FW release for your device. In your user guide - Chapter 12.5 is described how to use Dynamic DNS feature of your router.