Error "Unable to play 'Audible' access denied" happens every 4:16

All Sonos does, when you request Audible, or for that matter any streaming source, is to point the speaker to a server that they’ve been told to by the streaming company. In most cases, this is a separate server than that company’s own apps connect to. I have suspicions why, but it’s not important, the fact that it is a different server is the important part, and in your case, why there’s not a real value in comparing between Audible’s own app and the Sonos, they’re simply talking to two different sources. 

There’s a few of things I’d suggest, but I’m not 100% sure exactly what the issue is that your system is running in to, so much of this is speculative, and precautionary, and based on the anecdotal information you’ve provided. And unfortunately, Sonos doesn’t allow us to see the data in the diagnostics you submit, probably due to various privacy laws. 

Read the wifi interference FAQ, with the particular thought that the source of all Wi-Fi interference does not have to be from inside your network, or even inside your home. However, the 4:16 aspect does make this a lower possibility.

Remove Audible from your Sonos system, wait five minutes, the re-add it as a source. This will force a re-authorization of your credentials with the Audible servers. 

Refresh your network and Sonos. Unplug all of your Sonos devices from power. If your system includes a Roam or Move, make sure they are off, and not just asleep. Reboot your router. Give your router a few minutes to reload its OS, then plug back in your Sonos, and power back up any Roams or Moves in use.  This refreshes the router and the Sonos devices with fresh versions of their OS and a refreshed IP.

Test this unidentified book again. See if you can get past 4:16. Test another book, and see if that one can get past 4:16. 

If the second book works, and the first one doesn’t, the issue is with Audible, and not Sonos, and you should contact their support with your concerns.

If both books fail at 4:16, then it remains a Sonos issue, and I’d run diagnostics after each book’s failure and then call in to Sonos with those two diagnostics for them to compare. 

Thanks for the ideas, I really appreciate your thoughts I followed your steps exactly:

I read the wifi interference FAQ, but I didn’t do anything. When I talked to Sonos support, they keep telling me its interference based on the diagnostic code, but I don’t think that’s possible since I only have this problem on Audible.

1. I removed Audible from my Sonos
2. I waited five minutes and then added it back
3. I turned off my two Sonos One’s and made sure my Sonos Roam is off
4. I turned off the power to my router
5. I turned the power to my router back on
6. I waited a few minutes to the internet to come back
7. I turned on all of my Sonos products
8. The Sonos app couldn’t connect to my sonos system so I deleted the Sonos app from my phone
9. Reinstalled Sonos app to my phone
10. Reconnected my phone to the Sonos system
11. The Audible app was gone (XM Radio and Tidal were still there) so I reinstalled Audible to the sonos system
12. Tried the book again (the book in question is Watership Down) and it stopped at 4:13. I have tried other books as well and they also stop around 4:13 (or maybe 4:16)
13. I then tried Harry Pooter and the Sorcerer’s Stone and it also stopped at 4:13 - same issue as the first book
14. (I should note I can play audible on my phone - not thru Sonos - and I can listen to the book without problems)
15. (I wrote down the diagnostics # for future reference 1099039252)

A new issue that might provide a clue that also happened yesterday. The Harry Potter Book now won’t stop reading (this is after I started it again after 4:13). I would say “Alexa, stop” and then I would hear a noise and nothing would happen. Then I would press the stop button on the top of the Sonos One and it would just keep going (but an orange light would flash)...eventually it stopped once it hit another 4:13 of time. (At this point I should point out that the stopping at 4:13 is also an issue when I’ve tried my Sonos Roam, so the probably isn’t isolated to one Sonos speaker)

Reading through the steps, you haven’t actually changed anything (perhaps🤔?).. maybe manually set your routers 2.4Ghz WiFi  to a non-overlapping channel, use either channel 1, 6 or 11 and set the channel-width to 20Mhz only and ensure the SSID for that band is named differently to the 5Ghz band.

In the Sonos App Networks area, ensure it is set to connect to the 2.4Ghz band as the only Sonos network connection. Then give it another try after rebooting the speakers.

I have an Eero network and in my research it doesn’t look like I can change the channels. It does show I’m connected to channel 11 in the Sonos app