CAG not staying signed in for more than a few minutes

Using Chrome on tablet, Firefox on PC. CAG won't stay signed in for more than a few minutes, so the thread update icons keep disappearing. Is this a server-side signin issue? Cookie problem?

I can sign in and see the thread update icons that show new activity in threads, but within a few minutes they go blank (I guess I get signed out), then have to sign in again to get them back.

I also get this message often when trying to post: [#20310] Your secure key, used to verify you are posting the topic, did not match the one submitted. Please go back, reload the form, and try again.

Never mind, seems to be fixed now. I cleared cache and data on Chrome, and it's fine.