1:

 

2:

2b :   Check if  Self sign Certificate is uptodate if  using Https .

or else regenerate : https://draytek.co.uk/support/guides/kb-regenerate-certificate

3:

4: Check System Parameters – 59 and 60

5: Check Stun Settings

 

6: Check port 8069

7: Check Firewalls and open ports

8: Video on how to set TR069

Video