How do you have the Port currently wired?

Without looking in the Onkyo’s manual, I’d likely be connecting the Port’s line in to the zone 2 line out, and the Port’s line out to one of the four audio ins. There would likely be some programming of the line in involved on the Onkyo, though, I don’t own one.

Other receivers don’t send digital inputs like those HDMI ones to zone 2, I’d certainly want to double check that. 

The Port is a stereo device, as well, you’re never going to get an Atmos or even Dolby Digital signal through it. 

Thank you.  I had a longer reply but the forum ate it...So, in brief…

That’s what I have as connections.  I think the issue is in configuring the Onkyo and I have not found any decent support for that.  I will probably try o phoe or chat support with Sonos tomorrow.

Honestly, I’d try Onkyo support instead, especially if you can’t find the data in the Onkyo manual. They’re more likely to know their own equipment better than Sonos. But then it’s only time investment, there is no cost ;)

And sympathy on this forum eating your longer reply…it’s happened to me, too. 

Circling back to say that the issue is resolved. As both @Airgetlam and I suspected, the problem was not in Sonos port but in the (pretty non-intuitive) configuration of the Onkyo AV receiver.

Basically, sending sound from the Onkyo AV receiver (or the attached cassette deck or CD player) is accomplished by, in the event that someone else is looking for this information:

• Onkyo’s Zone 2 output → Port’s line in (RCA)
• Making Onkyo aware of Sonos port by having them both on the same wifi network and using Onkyo’s Hardware → Works with SONOS setup options.
• When one wants to actually send sound to the speakers, turn the Onkyo AV recevier on, use the Zone 2 button on the front of the receiver, then pick the source to send through Zone 2 by using one of the selectors on the front of the Onkyo (tuner, CD, NET, etc.) and then using the ‘Enter’ button on the front of the Onkyo receiver.
• One decides whether to control volume from the Onkyo receiver (Onkyo Line out ‘Fixed’ rather than variable) or using Sonos (either on the speakers or using the Sonos controlloer app).

Kindy of kludgy but it works. I can now stream through SONOS port to my SONOS speakers and use the iPhone app to determine which speakers or speaker groups to use.

And my thanks to the woman who saw my post, contacted me, and walked me through it. There’s a place in heaven for people who do that.

 And a big thumbs-up to you too, @pheski, for your “thank you”. I’m amazed how few people say thanks after they get help on these forums.