Comment 4 for bug 1316634

The solution:
Uncomment the code which has been commented out due to an already fixed gnome bug. This fixed the issue for me. Please confirm that it does fix it for you, too.

michael@thinkpad:/etc$ git diff NetworkManager/dispatcher.d/01ifupdown
diff --git a/NetworkManager/dispatcher.d/01ifupdown b/NetworkManager/dispatcher.d/01ifupdown
index ebadfd1..f4de9cc 100755
--- a/NetworkManager/dispatcher.d/01ifupdown
+++ b/NetworkManager/dispatcher.d/01ifupdown
@@ -55,16 +55,16 @@ for i in $ADDRESS_FAMILIES; do
             ;;
 # pre-up/pre-down not implemented. See
 # https://bugzilla.gnome.org/show_bug.cgi?id=387832
-# pre-up)
-# export MODE="start"
-# export PHASE="pre-up"
-# run-parts /etc/network/if-pre-up.d
-# ;;
-# pre-down)
-# export MODE="stop"
-# export PHASE="pre-down"
-# run-parts /etc/network/if-down.d
-# ;;
+ pre-up)
+ export MODE="start"
+ export PHASE="pre-up"
+ run-parts /etc/network/if-pre-up.d
+ ;;
+ pre-down)
+ export MODE="stop"
+ export PHASE="pre-down"
+ run-parts /etc/network/if-down.d
+ ;;
         hostname|dhcp4-change|dhcp6-change)
             # Do nothing
             ;;
michael@thinkpad:/etc$