Activating IPv6 without crashing IPv4

OK, I know it's possible to activate IPv6 BEFORE configuring Interfaces, but my experience yesterday was that activating it on my lab UTM crashed IPv4 - both the cable modem and UTM had to be rebooted to get IPv4 going again on the External interface.  Since my wife's the SOX coordinator, change-control coordinator and DR coordinator for a large organization, she wasn't happy that I took us down for 15 minutes!

After I activated IPv6, I went to the External interface definition and saw that it did not include options for both IPv6 and IPv4 - only IPv6.  Is this a known bug in 9.703-3?

Cheers - Bob

  • Hello Bob,

    Thank you for reaching out!

    I did these tests:

    1.- Only had IPv4 configured, went to IPv6 and enable it, checked and IPv4 was there and IPv6 address was ::

    2.- Set IPv6 address manually save and then disable IPv6 and re-enable IPv6, both IPv4 and IPv6 were there

    3.- Set IPv4 and IPv6 for Dynamic, disabled IPv6 re-enable IPv6, all good

    4.- Set IPv4 for Dynamic, set IPv6 manually, disabled IPv6 re-enable, no change.

    In all cases a lost a Ping when disabling and enabling IPv6.


    Emmanuel (EmmoSophos)
    Community Support Engineer | Sophos Technical Support
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  • I just did another test.  After activating IPv6, I saw the following with no IPv4:

    I immediately de-activated IPv6 and my IPv4 connection was still active.  Now, I'm suspecting my cable modem (CISCO DPC3010 Rev 1.0) or the ISP.

    Sophos UTM Community Moderator
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