AirPlay stopped working through the volume icon, still works through iTunes

System audio redirection via AirPlay stopped working on my Sierra macbook.

I'm able to AirPlay to my Airport Express directly from iTunes, however.

Changing the system clock on my macbook back a few days makes it work again!

More about it here. You're not alone.

https://forums.macrumors.com/threads/airport-express-ii-airplay-streaming-suddenly-stopped-error-10.2272599/

What model is the Express? (Gen1 or Gen2)

What firmware is it running?

Screenshot from Airport Utility is a big help.

You seem to have tried most things.. from the Mac and Express side.

What about the network?

How is the Express connected into the network? (wifi or ethernet)

What about the Mac, ethernet or wifi?

Are you using any airport router as your main router or different brand? Make and model for the later.

When you look at the network preferences for the Mac, it would help to know DNS and search domain. Screenshots help no end.

Open a terminal and type

ping (network name of the Express)

eg

Express named ex1 (much easier with short names, no spaces and pure alphanumerics)

So in terminal

So weird.. the computer is dumb.. cannot find the Express.. but airport utility and iTunes has no problem.

Issue could be domain.

Also could be DNS is public google address and it may need local router.

Change DNS to local router.. did not help.. probably hoping too much.. but I am using a Synology main router.. just BTW.

Added the domain to the name..

ie ping ex1.local

(Apple routers are always local domain)

Success.. so in the Mac put in local as domain in network preferences.

now ping without the domain.. it should search local by default.

I put in new domain but did not apply in preferences. As expected it failed.

I then applied the domain.. and the next ping succeeded.

The Express is now locatable on the network. And responding to pings.

Just to make things solid.. I would also give the Express a static IP.

Go to internet tab in the Express setup in the airport utility.

Change to static.

The existing IP will stay and everything else should be OK but you will need to type in a DNS because it is no longer handled by DHCP. Your main router IP immediately above the DNS value should be fine.

Computer should now have Express as a sound target.

Having done all this you still might need to downgrade firmware.. there are known bugs in the 7.8.1 firmware. Especially the Gen2 Express.

Hold down the option key and click the number of the firmware.. go back to 7.6.8 or thereabouts.

Tell me if it helps or where you get stuck.. more and more screenshots helps loads.

The Express is extending an existing wifi network.

The Express can join an existing non-apple router wifi network but cannot extend it.

The fact you are using a non-apple main router is giving you at least part of the problem.

Check you can ping the Express when the unit is not working. If it is not responding to pings change the domain as I suggested and see if it works.

It sounds like your Express is not working particularly well though.. so it may simply need replacement.

"By setting the system clock to an older date it does connect.

However, sound redirection doesn't seem to be working."

For me, if it connects, it works (plays sound via AirPlay). Is it different for you?

Regarding the certificate and solution to this problem, I'd like to hear someone from Apple Support comment on this.

Regarding the certificate and solution to this problem, I'd like to hear someone from Apple Support comment on this.

Just a quick note to mention that........No one from Apple Support will comment on this user-to-user support forum, so please do not wait to see if they might respond......because they won't.

To be fair, it's not solved solved. Just a workaround.