'World' LED on DIR-615 router keeps blinking,

Hi,

As stated in the topic, the 'world' LED on the router keeps blinking (was static previously). Everything works fine ( I can get online, etc), but I would like to know the cause of this.

Checked router settings - no other device connected
No downloads/uploads in progress (wifi LED not blinking as expected)
Tried restart router + PC

Basically there should be (almost) no traffic going through the router but that icon is still blinking rapidly. I can't figure it out. Any help would be great.

Thank you