Automatically connects to wifi though already connected to wired; plus even if previously explicitly disconnected from wifi

[teo1978]

I have a wifi network to which sometimes I connected and stored the password.
I am connected to the wired ethernet network.

Expected: shouldn't ever connect to any available wifi while I'm connected to wired.

Observed: sometimes, randomly, it automatically connects to the wifi despite the fact I'm already connected to wired. As a result, I am then connected to both.

Also, it does so at a completely random time: I've been here for hours, the wifi has been available for hours, I've been connected to the wired network all the time, nothing special has happened, I haven't restarted the commputer or logged out and in or anyhthing (I don't know if the wifi has become unavailable for a very short interval of time and then available again, it's unlikely and it wouldn't in any way justify the behavior), yet for some reason, NOW my computer decides to connect to the wifi (which it shouldn't anyway for any reason).

ADDITIONALLY:

After that, I explicitly manually disconnect from that wifi network. When I do this, I expect that the setting to automatically reconnect to this wifi network when available is turned off (otherwise, every time you disconnect from a network, it would reconnect immediately). I'm pretty sure this used to work.

But then, the same as described above happened AGAIN: that is, I was connected to the wired network (had been for hours), and suddenly it automatically connected to the same wifi network as above (again, been available forever), which it shouldn't even if it was set to automatically connect whern available (given it's connected to wired), but it isn't even more nonsensical given that I had previously manually disconnected from it so it should not be set to reconnect automatically.

This has started happening recently.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: network-manager 1.2.6-0ubuntu0.16.04.3
ProcVersionSignature: Ubuntu 4.4.0-148.174-generic 4.4.177
Uname: Linux 4.4.0-148-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Jun 4 18:35:11 2019
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2013-10-11 (2061 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
IpRoute:
 default via 192.168.1.1 dev eth0 proto static metric 100
 192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.37 metric 100
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.NetworkManager.NetworkManager.conf: 2015-02-20T16:52:59.722501
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH
 eth0 ethernet connected /org/freedesktop/NetworkManager/Devices/1 Wired connection 1 662a0c09-71a8-4101-9236-ebcc1696d69a /org/freedesktop/NetworkManager/ActiveConnection/2
 wlan0 wifi disconnected /org/freedesktop/NetworkManager/Devices/0 -- -- --
 lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/2 -- -- --
nmcli-nm:
 RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN
 running 1.2.6 connected started full enabled enabled enabled enabled enabled