I have version 2862 DrayTek it shows when i choose product registration to renew DrayDDNS license it it shows this error "myvigor.draytek.com refused to connect."
I'm unable to access the URL via the router.
and the firmware is already up to date.

I'm getting the same on a customers 2862 with the latest firmware avaiable.

You can follow these steps going to:
1- Application
2- Dynamic DNS
3- Click on 1. beneath Index or what the number your interface in
4- Click Sync Domain
5- After Syncing Select Edit domain
the page will open to enter the credential

I'm getting the same problem. I can access https://myvigor.draytek.com/ in my browser, but the router just says: myvigor.draytek.com refused to connect.

I'm having the same problem too

I have found the problem and contacted support about it. The issue is: Refused to display 'https://myvigor.draytek.com/' in a frame because it set 'X-Frame-Options' to 'sameorigin'.
In other words, the developers have told "https://myvigor.draytek.com" that it's not allowed to run in an I-frame, so the router simply cannot load the contents.