Unable to download package lists

Every time I start the PC and the system loads Zorin OS 15.3 Core, the internet icon gets a question mark.

It browses the internet anyway, but makes it impossible to enter Zorin's website, Zorin forums and even update the system using updates and software.

But after the internet icon goes back to normal without the question mark, it is able to enter the Zorin website, forums and even search for updates.

What can this be?

I get the same thing. Seemed to happen maybe after a certain kernel update or something months back. As wifi works, I have ignored it, but is not tidy.