I had the same issue with Sonos Radio HD on my home network (500Mbps). I could only stream it successfully if Sonos was connected to a mobile hotspot! I had no issue playing Tidal HiFi which streams in FLAC, similar to Sonos Radio HD, but Sonos Radio HD would just not play well.

When playing Sonos Radio HD do you sometimes get no artwork on the Sonos app even although music is playing?

Also how responsive is your system? Is it almost instantaneous or does it take a few seconds for actions to take effect?

From my experience, the most likely cause is WiFi interference.

Check your router is not broadcasting on the same channel as SonosNet (if you have a wired setup)

If you can, I’d wire as many speakers as possible to the router to create a stronger connection between them.

Even with SonosNet, I struggled to play one HD radio track without it dropping on any Channel (1, 6 and 11). Literally tried everything to get it to work without success. Lost count how many times I rebooted router and speakers.

As a last resort, I purchased a Sonos Boost to add to my system (Due to a router flaw, I can only wire 1 speaker directly to my router)

First day, with Boost wired directly to router and a system with only one Play:1, still had the same issues with Sonos Radio HD

Spent nearly 2hrs talking to Sonos Support and sending various diagnostics. Still no joy.

Day two with Boost and suddenly it just started working! Played over an hour and had no dropouts, which I’d never been able to do before. Sonos Radio HD worked flawlessly! It did drop out again a day or so later for a few hours, but since then had no further issues. I even played 3 separate Sonos Radio HD stations to different rooms at the same time without any dropouts.

I have since purchased a couple of Netgear switches so that I can wire additional speakers to my router. Overall, my system is now more responsive, with actions taking effect almost instantaneously, whereas sometimes they could have taken a good few seconds before.

Thanks for the detailed reply. It gave me things to try which helped out a lot. My issue ended up being the Apple Airport Extreme. Not that there was anything wrong with it. It’s an 802.11a/c…. the Sonos seems to only support a/n which means all speakers were getting less that 10mb because they connected at ‘a’ speed. Enough for Pandora but not enough for HD radio….. Swapped out the wifi for a Nighthawk with range extenders and poof. HD radio plays like a champ