systemd: depend on networking-online.target

Related: SYS#6400
Change-Id: Idadcbbf55e976ae035cfac4b85ccd870e0f27b82
diff --git a/contrib/systemd/osmo-gtphub.service b/contrib/systemd/osmo-gtphub.service
index 1e8f1ae..9ade246 100644
--- a/contrib/systemd/osmo-gtphub.service
+++ b/contrib/systemd/osmo-gtphub.service
@@ -1,5 +1,7 @@
 [Unit]
 Description=Osmocom GTP Hub
+After=network-online.target
+Wants=network-online.target
 
 [Service]
 Type=simple