Devolo ISDN router fix

Keywords: devolo, isdn, router, network, ssh, icq
Versions: firmware 3.42.0018 / 15.11.2004

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.

Related notes for 'ssh':
SSH & OpenVPN perform poorly

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