networkmanager problem wifi interface stops

[imesg]

About every two minutes I get the following in the journal:

Sep 01 15:42:35 go systemd[1]: Starting Network Service...
Sep 01 15:42:35 go systemd-networkd[4061]: Enumeration completed
Sep 01 15:42:35 go systemd[1]: Started Network Service.

After boot the interface stops at the same time as the first one of these journal entries.

ifconfig shows interface normal:

wlp0s29u1u7i2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.2.9 netmask 255.255.255.0 broadcast 192.168.2.255
inet6 fe80::26fd:52ff:fe82:779b prefixlen 64 scopeid 0x20<link>
ether 24:fd:52:82:77:9b txqueuelen 1000 (Ethernet)
RX packets 2237 bytes 1242709 (1.1 MiB)
RX errors 0 dropped 646 overruns 0 frame 0
TX packets 1287 bytes 468995 (458.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

When I boot up and start an continous ping the interface will not stop.

Any help appreciated.

Thanks

[imesg]

EDIT
**********This doesn't work 100%. wifi stays up longer then fails as before. Must be some interaction with something else****************
/EDIT

If anyone is interested, there is a temporary solution for this problem.

There are two systemd services, systemd-networkd and NetworkManager.

The names imply that there are two services which are controlling the network. This pertains to wifi not wired. Wired if not affected.

If I disable systemd-networkd and leave NetworkManager enabled then wifi (wlp0*) works. If both are enabled then the systemd-networkd starts on a two minute cycle. One minute after the start systemd-networkd stops. There is no log entry to indicate why. Every time it starts the wlp0* stops routing although ifconfig shows the interface up. If a continous ping is running then wlp0* will continue to route, not otherwise.

I don't think this is intended behaviour and would like to have systemd working properly.

Any thoughts which lead to a better understanding of systemd are appreciated.

Thanks