Hi there.
First of all, please don’t give up on Jami. It is excellent, despite some quirks. The Jami development team are, in my experience, excellent, and the product is progressing nicely. Well done to them.
Second, I have first hand experience of running Jami on Kubuntu, Ubuntu, and Android, and second hand experience with Apple, and some of Windows.
With Apple, the users I know of always find that their Jami goes offline. This seems to be a “thing” with Apple, possibly closing the port to save a (miniscule) amount of battery, but the net effect is that Jami becomes dead to the outside world. As far as I know there is no work around.
With Android, I have had excellent results. But, and it’s important, all battery saving must be disabled for Jami. If it isn’t then, again, Jami becomes dead to the outside world, and “missed call” is all you’ll see from it.
With Ubuntu – and this is on a laptop – (20.04lts) I’ve found that Jami does “go to sleep”. I had found a work-around to this, but the most recent update seems to have cancelled out my work-around (see Jami - Linux & Android - Requires Toggling Offline/Online (Disable/Enable) (#1456) · Issues · savoirfairelinux / jami-project · GitLab). “Wakening” Jami seems to require toggling the account enable/disable button. I now need to upgrade the Ubuntu to the newest version to see if the problem goes away.
With Kubuntu (on a desktop, running 24/7, and again 20.04lts), I have had no issues at all. 100% working all the time, and excellent.
The only user I know of with Jami on Windows may not be entirely reliable, so the results are probably not worth considering.
With regard to linking your account across several devices, I have found that unless Jami is running on all those devices pretty much all of the time, there can be some kind of latency regarding synchronisation. I generally don’t link devices, opting to have an account for my desktop, one for my laptop, and one for my tablet. But when I have linked my desktop to my tablet, I have found this works well, and I assume this is due to them both being on 24/7.
Do remember; with Jami, you are the server. There is no intermediate server, à la WhatsApp (yuk!) or whatever. If your machine is off, or simply offline, nothing will flow.
Finally, I have all options in OpenDHT Configuration set to off, and only TURN set to on in the Connectivity settings.
I hope this gives you some pointers. But I stress, don’t give up! Jami will reward you when you have your system set up for it.
Did I mention, don’t give up?!?! 