FAQ Set "mdex EASY SIM" (KPN) to MTU 1120

With mdex EASY SIM (KPN SIM), the MTU (Maximum Transmission Unit) 1500 can cause transmission interference and aborts, especially when transmitting larger UDP data packets. For interference-free data transmission, the MTU 1120 should be set in the mobile settings!

Below you will find informations how to set the MTU 1120 in mdex Routers:
mdex router MX530 / MX880
mdex Router MX560
mdex Router MX760
Teltonika RUT-Series

mdex Router MX560

Click on Network -> Mobile, enter the value 1120 for MTU and click on Save.

mdex Router MX760

Under Configuration click on Mobile WAN, enter at MTU the value 1120 and click on Apply at the bottom:

mdex Router MX530 / MX880

Since MX530/MX880 firmware version 02.453, the MTU can be set directly via the web interface.

Click on Network -> Mobile (SIM), enter the value 1120 for SIM1 or SIM2 as MTU and click on Save.

ALERT! If the parameter MTU is not displayed here, please make a firmware update to the current version.

Here is the old method for setting the MTU up to MX530/MX880 firmware version 02.400:

  1. Click on System --> User Scripts, enter the following commands in Startup Script Management and click on Save.
    uci set network.ppp.mtu=1120
    uci commit 
  2. Reboot the router at System -> Reboot so that the commands for setting the MTU 1120 will be executed.
  3. The MTU setting is permanently saved in the data set with uci commit, so the set commands can now be deleted again under System --> User Scripts.

Teltonika RUT series

Until firmware R_00.06.(old style):
  1. Click on Network -> Mobile Configuration.
  2. Enter the value 1120 at MTU and click on Save.

Up from firmware R_00.07.00 (new style):
  1. Click on Network -> *Interfaces
  2. Click on Edit for the mobile interface (MOB1S1A1).
  3. Click on ADVANCED SETTINGS, enter the value 1120 at Override MTU and click on Save.