diff --git a/boards/sim/sim/sim/configs/rpproxy/defconfig b/boards/sim/sim/sim/configs/rpproxy/defconfig
index 385bcd36fb8..2d347ebe5d4 100644
--- a/boards/sim/sim/sim/configs/rpproxy/defconfig
+++ b/boards/sim/sim/sim/configs/rpproxy/defconfig
@@ -38,6 +38,7 @@ CONFIG_NETDB_DNSCLIENT=y
 CONFIG_NETDB_DNSCLIENT_MAXRESPONSE=176
 CONFIG_NETDB_DNSCLIENT_RECV_TIMEOUT=3
 CONFIG_NETDB_DNSSERVER_IPv4ADDR=0x771d1d1d
+CONFIG_NETUTILS_IPERF=y
 CONFIG_NET_RPMSG=y
 CONFIG_NET_USRSOCK=y
 CONFIG_NET_USRSOCK_ICMP=y
diff --git a/boards/sim/sim/sim/configs/rpserver/defconfig b/boards/sim/sim/sim/configs/rpserver/defconfig
index e3020a2a5ad..fbe68c5a8bc 100644
--- a/boards/sim/sim/sim/configs/rpserver/defconfig
+++ b/boards/sim/sim/sim/configs/rpserver/defconfig
@@ -30,6 +30,9 @@ CONFIG_FS_RPMSGFS_SERVER=y
 CONFIG_IDLETHREAD_STACKSIZE=4096
 CONFIG_INIT_ENTRYPOINT="nsh_main"
 CONFIG_INPUT=y
+CONFIG_IOB_BUFSIZE=256
+CONFIG_IOB_NBUFFERS=512
+CONFIG_IOB_THROTTLE=32
 CONFIG_IOEXPANDER=y
 CONFIG_IOEXPANDER_RPMSG=y
 CONFIG_LIBC_HOSTNAME="server"
@@ -45,6 +48,7 @@ CONFIG_NETDEV_STATISTICS=y
 CONFIG_NETINIT_DHCPC=y
 CONFIG_NETINIT_THREAD=y
 CONFIG_NETUTILS_DHCPC=y
+CONFIG_NETUTILS_IPERF=y
 CONFIG_NET_ARP_SEND=y
 CONFIG_NET_BROADCAST=y
 CONFIG_NET_ICMP=y