I have 3 types of connection: * LAN with priority p=10, * WiFi with p=5, * 4G/LTE with p=-1. The active and working connection with the highest priority is not activated when it should be. Example: 1) There are no active connections. 2) I activate modem p=-1 and it is active and working. 3) Then I activate WiFi with p=5, the connection is established but it is not activated and the system is still using modem. I am Manjaro KDE and in the past when I was on Kubuntu this was working fine...
The "priority" property you talking about is "autoconnect-priority", which means that it is taken into account when there are e.g. more available wireless networks at the moment and this helps to decide which should be activated. It has no effect on device priority. It's NetworkManager who decided which device should be the default one.
OK, I will try to use metric of each connection whether it helps. It's just annoying that when I plug in a cable my LAN connection is not chosen as the default one and the system still uses modem.
@Jan Grulich Out of curiosity - do you know why a magic number of 20000 is being added into connection's metric? https://unix.stackexchange.com/questions/444538/metric-on-connections-and-magic-20000-value-added