I have a Hauwei 1port modem which has developed a rapid constant flashing port1 light. This started a little while after openreach replaced the power adapter which had failed. The Bt and openreach help pages suggest that there could be a problem with the router connection which I have checked, or the router itself. There does not appear to be noticeable loss in speed or service but it has become distraction.
Try unplugging the cable to your router, does the flashing stop 🤣
The flashing light indicates an active connection and is normal, I suspect it's not so much that it's just started - more likely you've only just noticed it
