# Setting wireless mtu?



## vsoto (Aug 3, 2011)

Hi,

I have an ADSL connection that gets dropped very often (I can ping the modem-like device but nothing further). This can happen when doing a google image search and scrolling fast, for example. 
Some googling revealed that putting the mtu of the network interface to 1492 should fix the problem. I tried it with a wired connection and the solution seems to work but when I tried it with the wireless connection it didn't work. From *ifconfig*:


```
(01:10:24 <~>)0 > ifconfig
re0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1492
	options=389b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_UCAST,WOL_MCAST,WOL_MAGIC>
	ether 00:03:25:50:e5:9e
	media: Ethernet autoselect (none)
	status: no carrier
wpi0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 2290
	ether 00:1f:3c:66:ab:0d
	media: IEEE 802.11 Wireless Ethernet autoselect mode 11g
	status: associated
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
	options=3<RXCSUM,TXCSUM>
	inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3 
	inet6 ::1 prefixlen 128 
	inet 127.0.0.1 netmask 0xff000000 
	nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1492
	ether 00:1f:3c:66:ab:0d
	inet 192.168.1.96 netmask 0xffffff00 broadcast 192.168.1.255
	media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g
	status: associated
	ssid Ginnungagap channel 1 (2412 MHz 11g) bssid 00:25:3c:93:ba:aa
	country US authmode OPEN privacy ON deftxkey 1 wepkey 1:40-bit
	txpower 0 bmiss 7 scanvalid 60 protmode CTS roaming MANUAL
```

While wlan0 has mtu=1492, wpi0 has mtu=2290. I can set the mtu of wlan0 to 1492 but when I try to set the mtu for wpi0 I get:


```
# ifconfig wpi0 mtu 1492
ifconfig: ioctl (set mtu): Invalid argument
```

How can I change the mtu value for wpi0?

Thanks,

V.


----------



## SirDice (Aug 3, 2011)

It's not going to help you even if you manage to set the MTU on wpi0.


----------

