systemd: depend on networking-online.target

Related: SYS#6400
Change-Id: I9c0cc0779f9ddb7520a565668b7cde07c6ad55d8
diff --git a/contrib/systemd/osmo_dia2gsup.service b/contrib/systemd/osmo_dia2gsup.service
index df56e71..b57247b 100644
--- a/contrib/systemd/osmo_dia2gsup.service
+++ b/contrib/systemd/osmo_dia2gsup.service
@@ -1,6 +1,8 @@
 [Unit]
 Description=Osmocom DIAMETER to GSUP translator
 After=osmo-hlr.service
+After=network-online.target
+Wants=network-online.target
 
 [Service]
 Type=simple