If you've already tried some troubleshooting but you're still having troubles, it would be really helpful sharing the details @Xenia requested here so we can get this reported with the right folks.
Keep in mind we'd recommend including as many details on what's exactly happening as possible (for example, the exact steps you take when this happens) - this helps the teams investigating better reproduce this on their end.
We'll be keeping an eye out for your replies, thanks!
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"Kindness is the language which the deaf can hear and the blind can see." - Mark Twain
Device details (build/model/OS): iPad Gen 6 iOS 14.0
Speaker model + firmware version: Bose Soundtouch 10 software version 25.0.0; Soundtouch app version 26.0.1
Troubleshooting steps you tried so far. I followed the guidance on that post. I’ve reinstalled Spotify, restarted iPad a few times. Reconnected the speaker.
I recall seeing a Spotify update during the week to the iPad app. This loss of speaker has happened after that, though no idea if that has caused any change or not.
It’s been fine for ages, it’s stopped appearing within the last few days.
Also, I see you have marked the thread as solved based on a post a couple up where someone describes what they tried. Solved does seem a bit extravagant based on one person and a post that perhaps many, myself included, won’t even understand.
Having posted the message above I just did a further check on the Soundtouch app on iPad. Amazon music service - plays fine on Soundtouch 10 speaker. Deezer music service - plays fine on Soundtouch 10 speaker. Spotify music service - doesn’t play at all.
Maybe I need to swap my music service, it’s not a lot of use paying premium for silence.
@xenia anything you can add based on previous posts and info supplied?
As I have all my SoundTouch devices (SoundTouch 130, SA-5 and a SoundTouch Wireless adapter) in my cottage, I'm not able to test with the SoundTouch app since it doesn't present the services until it has contact with at least one compatible speaker.
BUT, after the fix to the bug I reported back in May got fixed (and it seems it's fixed in your version on the iPad as well) I've not had any problems.
As a wireless networking professional I can imagine that many of the problems reported in this thread are down to the network. There's often a lot of focus on the two peers in the playing: the app on the phone/table and the speaker. But the fact of the matter is that the networking infrastructure has a significant role in this as well. And though you would think that a wifi network is a wifi network, they can differ quite a bit as well.
It's not too uncommon by wifi vendors (whether it's access points (bridging devices) or routers/gateways (combined routing/NAT:ing and bridging)) to try to optimize traffic by filtering out traffic that is considered potential network hogs, and this often includes multicast traffic and/or broadcast traffic.
Since I can't look at how the SoundTouch device does discovery for the other services (the Spotify discovery is Spotify specific) I can't give the answer right now. But it could be that it uses broadcast traffic either to the global broadcast or local broadcast address (255.255.255.255 or 192.168.1.255 (if your network is 192.168.1.0/24)), and that the router/AP filters traffic for multicast but not for broadcast. What I do notice is that when using the Deezer app itself, it uses regular AirPlay discovery with mDNS. But Bose's app could use something else. (And theoretically there could be other things that affect the method chosen.)
Ideally one would do wireless packet captures to record the traffic and see what's actually sent and received. But this of course requires more skills than operating the Spotify app.
But until I get around to doing a more comprehensive guide on how to record wireless traffic (not promising one, but I'm tempted to do one based on all the problems people have, and the fact that wireless packet captures are really the best way to troubleshoot things like this) I would look in the wireless router or access point admin interface and look for any kind of broadcast or multicast suppression. You can also check if different radio interfaces(2.4GHz (802.11b/g/n/(and maybe even 802.11ax, since that supports 2.4GHz as well) and 5GHz (802.11a/n/ac/ax) are not segregated/isolated. If you have the same SSID (network name) on both radios there's no real way of controlling which channel your phone and speaker connect to. Of course, the segregation scenario is not likely to apply if other music services do work from the app. (But could be applicable for those struggling to get connection at all.)