diff --git a/diskimage_builder/elements/simple-init/post-install.d/80-simple-init b/diskimage_builder/elements/simple-init/post-install.d/80-simple-init
index 48913bc4d..5fcdc7add 100755
--- a/diskimage_builder/elements/simple-init/post-install.d/80-simple-init
+++ b/diskimage_builder/elements/simple-init/post-install.d/80-simple-init
@@ -48,5 +48,6 @@ if [[ ${DIB_SIMPLE_INIT_NETWORKMANAGER} != 0 ]]; then
     # Debian has a many year old long bug report detailing this behavior with
     # the most interesting comment being at the end:
     # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=755202#331
-    echo 'net.ipv6.conf.default.router_solicitation_delay=15' >> /etc/sysctl.conf
+    DIB_SIMPLE_INIT_NETWORKMANAGER_IPV6_DELAY=${DIB_SIMPLE_INIT_NETWORKMANAGER_IPV6_DELAY:-30}
+    echo "net.ipv6.conf.default.router_solicitation_delay=${DIB_SIMPLE_INIT_NETWORKMANAGER_IPV6_DELAY}" >> /etc/sysctl.conf
 fi
diff --git a/releasenotes/notes/simple-init-nm-delay-f579e05467785219.yaml b/releasenotes/notes/simple-init-nm-delay-f579e05467785219.yaml
new file mode 100644
index 000000000..3f1339e4d
--- /dev/null
+++ b/releasenotes/notes/simple-init-nm-delay-f579e05467785219.yaml
@@ -0,0 +1,11 @@
+---
+fixes:
+  - |
+    The ``DIB_SIMPLE_INIT_NETWORKMANAGER_IPV6_DELAY`` variable is
+    added for the ``simple-init`` element to set the
+    ``net.ipv6.conf.default.router_solicition_delay`` sysctl setting
+    (it defaults to 30s).  If you are seeing an extra "blank"
+    interface in ``nmcli con show`` it is likely that NM has not
+    correctly configured itself in the presence of an interface
+    already configured with IPV6 by the kernel.  Increasing this value
+    may help work-around the problem.