Hi Simon as a Google Pixel user you don’t get these options, and get to rely on Google’s good grace as to whether Roon stays running or not (and memory management seems much improved since the 3 was released).
On many other Android phones I have used Roon on, the optimization is the one thing that keeps the user from going mad and makes a big difference to the overall user experience.
Mike
Well not on the ones I have used OnePlus5 and The Pixel 4 they both have same behaviour. Same on my Samsung S6 but that had other issues like getting stuck initialising connection. So long ago now though since I had the Samsung. Once was enough for that crap, won’t ever buy another Samsung was a terrible experience.
Simon I don’t want to talk down Samsung users but my last Samsung phone was the S4 (Google edition, ok hacked on Google edition), and many of my friends have them and swear by them (not at them)
I had the OnePlus 6 when i started using Roon, and it started having issues with the update to Android 9 (if memory serves correctly though might have been 10), and the introduction of improved battery life, and they do this by force closing apps, especially if they do not have a permanent notification icon. This is apparently very popular in China and they want to advertise 2 day battery life.
I am not a fan of this behaviour but in general they do give you tools to manage this, if not making it easy and sometime override these settings after updates. As with many things Android it’s different per manufacturer so is even more annoying.
When I see people who have this problem, I point them to one of a couple of threads and I usually get a thank you back, so I guess it must work for many.
Regards
Mike
Sorry, I forgot to add the part about stopping apps from sleeping as @SukieInTheGraveyard mentioned.
Those options are mutually exclusive on the S20 Ultra. Selecting one deselects the other.
That’s also been my experience. I have other apps connected to servers and they’re all just fine. Roon is the only problematic app I have and it’s the only app I paid so much money for. Regarding the memory issue, I don’t think that should be a problem on my phone as it has 16GB memory. That’s as much as my macbook pro.
I don’t have connection issues, just the app closes the connection when in the background, it connects instantly it’s brought to the foreground.
It doesn’t sound like the app sleeping is the problem for you. I wouldn’t have thought that disabling battery optimisation or enabling sleep prevention would sort out your issues.
I know I’ve asked this before, but have you tried the 255.255.255.255 work around? It’s a bit tricky to keep on top of your responses as this goes across two threads! 
I just tried the 255 work around. After a few minutes I showed my core, but it’s showing the usual ip address. Should that be the case?
This seems to be issue with Roon not working with the S21 Ultra. My S20 Ultra worked fine after a few tweaks and my S21 has those same tweaks. I just broke out my old Note 8 and it works great - the app opens instantly, which is why I prefer using android remotes over apple. Apple remotes tend to take a second or two to open, which can be a little frustrating.
One would think roon would get popular phones for testing purposes and deal with these issues before the consumers face them, but their quality control efforts are laughable.
Thanks, Dirk!
The problem seems to be with Android implementation, which varies considerably from manufacturer to manufacturer. This means that Roon developers are having to make reactive adjustments. If manufacturers stuck to established protocols, particularly over multicast, then things would be easier. Before Roon developers can do anything they need to replicate the problems that people are identifying. That’s not always easy, bearing in mind that there can be a myriad of variables to take into consideration (Core Device, Network set up etc.).
I understand that you want to get things working on your S21, but if you have other remotes then can’t you just use one of them for the time being?
Ask any developer how difficult it is to make a system integrate with Android, especially one as complex and muti-functional as Roon. By comparison, iOS is a breeze - there’s only one implementation and it’s Apple’s own and there are limited numbers of devices. Every Android device manufacturer puts its own spin on the OS and then customises it further for each device and there are literally hundreds, maybe thousands of different Android devices.
Roon’s efforts at keeping on top of all of this are laudable.
[Moderated]
EDIT: Apologies if my impassioned language offended, but real, thinking, feeling human beings work very hard on this stuff.
Nobody told me I needed a full datacenter with DR when I signed up for Roon 
I’m currently using the Note 8 as a remote, but that’s not acceptable in the long term. I don’t want to carry two devices around the house just so I can use roon.
Unfortunately, the 255 workaround didn’t fix the problem.
My Samsung Note 10 went through two software updates this week, yet Roon cannot connect to the only core, where two weeks ago worked fine.
Just now, several minutes has gone by, finally asked do you want to connect to the core (well, duh?). If Roon is closed and restarted, it’s the whole wait again, if you wait long enough, like 3mins or so, Roon will find the core by itself. If the phone goes to sleep for a ‘while’, Roon client can’t connect again.
The not sleeping app didn’t work for me either.
The pain of updates goes to show where someone didn’t consider / forgot / couldn’t care less about xyz application, if enough users complain, then we can do something about it an look how it shows we care (pffft). People are paid to get things right, they do not deserve to be paid, a hard kick up the ar$e is what they need.
On the same Wi-Fi connection (TP Link mesh) not 1m away, a simless iPhone 8 plus boots up Roon straight away.
Mind I have also read of users where the same drama can occur on iOS devices, but have not experienced this myself on the 8 plus or iPad Pro (several years old now, still locked in landscape mode, that one).
A computer used as the control, never fails.
I’m guessing that was a little tongue-in-cheek…
My network probably isn’t typical - there’s a lot on it, but at the same time it’s actually very simple. It’s has a very flat structure. I see posts where people have multiple switches connected, daisy-chained, whatever. I’m not sure everyone realises that if you have a Gbit connection to a switch with 4 ports, and you then connect to that switch another Gbit switch with another 4 ports, you’ve potentially taken 1/4 of your available bandwidth from the first switch and divided it by 4 on the second. Your second switch could be down to 62.5 Mb/s per port…
I know it isn’t. But if it works, then it works. At least you can enjoy the music!
Which is still enough for audio.
I have an 100 Mbps connection from my service provider, so I will never get 100Mbps from Qobuz.
Still working perfectlyfine, even when I listen to streamed 192kHz/24bit
And sorry, but this is nowhere related to the actual topic of Andoid remotes not-connecting
Dirk
But complain to who? If your remote device is updated and then doesn’t work with Roon then that’s nothing to do with Roon. Of course Roon may be able to work on a solution, but the problem is caused by a Samsung update. It’s just the nature of the beast when it comes to the messy nature of Android devices.
The price we pay for open sourced free software?