Thanks to both of you, I know 2 ways to solve the issue.

II used schturman's method listed in the link, and it fixed it . I did not want to lose all connections.

Based on schturman's post, I believe this issue was triggered when I was playing with the wlan search interval using gconf command, and tried to automate it using ProfileMatic. I guess I should find some other safe way to disable wifi or wifi scan.

Thanks a lot to this awesome community

Now back to waiting for my Jolla phone.