@Alan07 

Hi Alan, 

To help you troubleshoot the issue with not being able to connect your fibre cable to your ASUS router, please check the following:

1) Have you checked the configuration settings of your router? It is possible that the configuration may be incorrect or wrong.

2) Have you tried a different cable or port on the router? This could help determine if the cable itself is causing the issue.

3) Check if the light on the unit is connected correctly and working properly. If not, then the connection may be faulty and you may need to replace it.

I hope that this helps in resolving your issue.  Good luck!