diff --git a/rootfs_overlay/etc/unbound/unbound.conf b/rootfs_overlay/etc/unbound/unbound.conf
index 4b65228..b1e8cdd 100644
--- a/rootfs_overlay/etc/unbound/unbound.conf
+++ b/rootfs_overlay/etc/unbound/unbound.conf
@@ -86,6 +86,9 @@ server:
     # (requires CAP_NET_ADMIN or privileged)
     # so-rcvbuf: 1m
 
+    # Set to 0 to use system default and avoid startup warnings
+    so-sndbuf: 0
+
     # Increase cache size to utilize more RAM
     msg-cache-size: 64m
     rrset-cache-size: 128m