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VLAN subnet extension. New addresses unusable.


I have increased the size of a subnet from /27 to /26 and any node with an IP beyond the range of /27 has connectivity issues.

I have done this before and don't remember having issues. Apart from Network > Interfaces > VLAN > {Port} > IPv4/netmask, is there anywhere else I need to go to make changes?

The XG is the only layer 3 device on the network. Switches are all layer 2.

XG and switches have been rebooted several times.

XG version: SFOS 19.0.1 MR-1-Build365 (My device hasn't picked up 19.5 yet and I can't find the option to manually upload).

I've checked the routing table from the advanced console with route -n and the VLAN in question has the correct mask (

Thank you.

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  • Hi,

    to upgrade to v19.5 you need to manually download and install. Are you using the XG DHCP server? If so have you changed the range?

    What have you defined in your firewall rule for source network?


    XG115W - v20 GA - Home

    XG on VM 8 - v20 GA

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  • I think I have found it.

    Under: Hosts and services > Name: VLAN[ID]. The address detail had the old subnet mask in there. I've updated the subnet mask and all seems well.

    I suppose that there was absolutely nothing in the logs should gave given me a clue.

    It's taken 3 days to troubleshoot the network connectivity issues I was experiencing, finally arriving here. Wow!