diff --git a/examples/gnrc_border_router/Makefile b/examples/gnrc_border_router/Makefile
index a0e8d59f6d..d9e3929e32 100644
--- a/examples/gnrc_border_router/Makefile
+++ b/examples/gnrc_border_router/Makefile
@@ -67,6 +67,11 @@ else ifeq (static,$(PREFIX_CONF))
 # Only set this if the default router does not send router advertisements
 # IPV6_DEFAULT_ROUTER ?= fe80::1
   USEMODULE += gnrc_ipv6_static_addr
+
+  # configure static DNS server
+  ifneq (,$(filter sock_dns,$(USEMODULE)))
+    USEMODULE += auto_init_sock_dns
+  endif
 endif
 
 # Comment this out to disable code in RIOT that does safety checking
diff --git a/sys/net/gnrc/network_layer/ipv6/nib/_nib-router.c b/sys/net/gnrc/network_layer/ipv6/nib/_nib-router.c
index c7b15e5beb..4a61df12bd 100644
--- a/sys/net/gnrc/network_layer/ipv6/nib/_nib-router.c
+++ b/sys/net/gnrc/network_layer/ipv6/nib/_nib-router.c
@@ -155,7 +155,8 @@ static gnrc_pktsnip_t *_build_ext_opts(gnrc_netif_t *netif,
     uint32_t rdnss_ltime = _evtimer_lookup(&sock_dns_server,
                                            GNRC_IPV6_NIB_RDNSS_TIMEOUT);
 
-    if ((rdnss_ltime < UINT32_MAX) &&
+    /* with auto_init_sock_dns we always have a valid (static) DNS server */
+    if (((rdnss_ltime < UINT32_MAX) || IS_USED(MODULE_AUTO_INIT_SOCK_DNS)) &&
         (!ipv6_addr_is_link_local((ipv6_addr_t *)sock_dns_server.addr.ipv6))) {
         gnrc_pktsnip_t *rdnsso = gnrc_ndp_opt_rdnss_build(
                 rdnss_ltime * MS_PER_SEC,