I have recreated this closed topic as I have exactly the same issue as was so clearly described by other users.
Audible intermittently stops after playing for a few minutes. “Alexa resume” restarts it usually a minute or two before it stopped.
Alexa work fine otherwise and audible on other devices works fine. Its just the combination of Audible and Alexa on my Roam that has the problem.
Definitely not WiFi issue
Sonos - Please investigate this which is clearly a bug of some sort