500 series errors, including 504 come from the server not the client. So the Naim app isn’t generating the error but a proxy between it and the end service it’s attempting to access.
If the album notes are stored locally (on a device in your home) it will be a local issue. If they are fetched from the internet then a gateway you have no control over is likely at fault. Results would likely vary between countries.
We have been working with Rovi to get this fixed. It’s an intermittent issue where when a Rovi Search is done, it can fail to reply with an internal gateway timeout error.
Once Rovi have resolved the issue I will post an update.