Devolo ISDN Router Fix
The information on this page applies to firmware version "3.42.0018 / 15.11.2004".
Introduction
The router has a problem with connections that are inactive for more than 300 seconds. After this period of time the router will simply "forget" about a particular connection. As soon as data is to be transmitted again, a connection failure is caused.
The insufficient timeout will hardly be noticed while browsing the web, but some instant messengers as well as services like SSH suffer.
Instructions
Here is how the timeout can be changed:
- download configuration using the router's web interface
- replace line "1.2.8.9.1 = 300" with "1.2.8.9.1 = 7500" in the configuration file
- upload the modified configuration using the web interface
The value appears to be the time in seconds, for which the router keeps connection data. In Linux the TCP keep-alive interval is 7200 seconds, making a value of 7500 a safe bet. This may not hold true for other systems.
Notes
Mac, Linux: Be sure to preserve the CRLF at the end of each line. Otherwise the router will not accept the uploaded file.
This modification might have undesirable side effects. Connection data will be kept in memory longer than usual, possibly causing memory exhaustion in high traffic situations.