Dear Switzernet Customers,
We've detected an incompatibility problem between the last version of our servers and some old versions of Netgear routers. The problem was discovered following the last server updates carried out during December. Customers using these routers have complained that after migration they were unable to receive calls and that their outgoing calls dropped after 20 seconds. According to our current data, much of those customers are connected to the network of Cablecom.ch. There are customers using these routers also in the Swisscom.ch network.
From our tests it appears the router is erroneously changing the content of the messages sent by our servers or simply discarding them on other cases. The Netgear models affected by these problems are Netgear WNR1000 and WNR2000. It is possible to correct the problem on the router by upgrading its Firmware to a newer version or by disabling its SIP ALG and SPI firewall features. On the other hand, we are currently working on a solution that will bypass the problem of the erroneous firmware of these routers without having to change the router configuration.
We unfortunately do not know yet the precise number of affected and/or lost customers due to this error.
For more details regarding this problem you can consult the document available at:
http://www.switzernet.com/3/public/120106-dnatproblem/ [updated 2012-02-07]Best Regards,
Switzernet Team
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