Troubleshooting – Connection Problems with the KNX-IP-Interface

In this article we will show you what you can do, for example, in case of connection problems to your KNX-IP interface due to timeouts.

Top reasons for connection timeouts if only local (WIFI) access configured:

  1. Configured only for WIFI access but the mobile devices is not connected to WIFI.
    1. Turn on WIFI on your mobile device and connect to the right WIFI
    2. Make sure that you are in the range of the WIFI and have a good reception.
  2. Mobile device is connected to a different WIFI (in case multiple WIFIs are existing)
    1. Double check if it’s connected with the right WIFI which serves connection to the KNX IP interface/router.
  3. Wrong local IP address is used for the KNX IP connection of the ayControl profile.
    1. First check which IP has been statically assigned to the KNX IP interface/router. Ask your KNX installer or use a network scanner like „Fing“ or “Angry IP scanner” to find out the correct IP address.
    2. Make sure that the KNX IP device has been bound to a static IP. Otherwise the installation will not be stable e.g. after a power loss. How? This usually has to be done by the installer in the ETS program.
      Alternatively a static IP can be reserved and bound to to the so called MAC-address of the KNX IP device.
      This can be done in the local DHCP server (e.g. in your WIFI router). Look into manual or search for internet howto’s.
  4. Connection from WIFI to the KNX IP interface/router is disconnected or KNX IP device has no power
    1. Check cables and check if the LEDs of the LAN ports of the KNX IP device show activity.
    2. Check if the KNX IP device is correctly powered.
  5. If a WIFI system with multiple APs (access points)
    1. Make sure that the client maintains the same IP after the handoff from one AP to another.
    2. Make sure that clients have connection to the KNX IP device from all relevant APs.
    3. As KNX connections are using heartbeats: Make sure that the handoff is as fast as possible (below 1 second).

Top reasons for connection timeouts if using only port forwarding connection:

  1. Mobile phone is connected via 3G/4G or wifi and never connects using the configured port forwarding connection.
    1. Is the port forwarding connection configured right? Please check the manual of your internet-router how to correctly set up a port forwarding connection to your KNX-IP-Interface.
    2. If the port forwarding is set up right, could it be that DynDNS (DDNS) isn’t configured properly?
  2. Mobile phone is connected via 3G/4G and sometimes a connection problem occurs.
    1. Please check the signal reception at that time. If the signal is too weak a connection to the KNX-IP-Interface might not work.
  3. Mobile phone is connected via 3G/4G and can’t connect to the KNX-IP-Interface but if the phone is connected to a (remote) wifi network (for example at a friend’s place) the remote connection works.
    1. In this case please talk to your mobile phone service provider. In some rare cases it could be that your mobil phone service provider blocks some network packets which prevent a successful remote connection.