Your settings are different or your antivirus is causing problems or your network isn't configured correctly. DLNA works in all those versions.
Check the Windows Defender thread on the MC27 board.
I really wish that was the case but I don't see any sign of it. I've gone through the "weird" thread and the antivirus thread every year or so when the upgrade offer comes and it bugs me.
Defender is not on, it's Bitdefender but there is no sign of any interference. And I'm well familiar with its interference, it has done it in the past - but then the interference would show in the bitdefender log. There is nothing in the log except that these programs are allowed out
So on this machine I am on now:
minutes ago I had only MC24 and it played fine to the speaker - "send to" and it plays.
I can see the playlist on the zone, I can see the volume level, playing progress, and it all fits.
I close MC24
I install MC27. I run it, set up media server and see the notification in bitdefender it is allowed automatically.
MC27 shows me the speakers as zones fine.
I try "send to" in MC27, and MC thinks it's playing but nothing is coming on the speaker.
Close MC27, open the MC24 that worked perfectly fine 30 minutes ago, but now "send to" isn't working anymore in MC24 either.
Nothing has changed in my network, computer, or firewall/virus scanner. All that has changed is adding MC27.
If I can understand what is different, I can figure out if the issue is network (eg: it uses newer dll, newer protocols, more bandwidth) or some security somewhere or the devices arent compatible - but then whitebeard managed to analyse fine.
Wish I could find some logs for MC server, are there some somewhere?