Sometimes connection between my phone and PC is lost: PC KDE connect shows 'No paired devices available'. It always happens when phone screen is off but wi-fi is connected and it can be pinged from the PC running KDE connect. When phone is turned on connectivity is restored immediately and before it is unlocked. KDE connect android app is excluded from the battery optimisation list. It doesn't happen often - probably about once a week, and I failed to notice a pattern. Android 9, Caterpillar S61. Android app is at the latest version but linux client is not: 1.3.3 (ubuntu 18.04). My question is: will upgrading linux client help to resolve this issue or is it something else?

I think the problem is more likely on the Android side, make sure you have all the priorities set for Bluetooth and KDE Connect on that side.