Searched forums for 'swap' for no hits.
Loading 7.10 CDs on a laptop. Internal NIC to be internal network (MUST BE - disconnected gateway, house still works. Other way around ... not.)
On a different disk, used DVDs - problem below didn't occur.
USB NIC to be external.
Internal NIC came in as eth1, usb eth2.
With CDs loaded, no swap interface button on admin web page.
Following link above failed, until I noticed a missed step (the first one) -
Web Admin: Show devices tree/My Devices/CORE > Device data/Network Interfaces
* Change: eth0,dhcp|eth0:0,192.168.80.1,255.255.255.0 to: eth0,dhcp|eth1,192.168.80.1,255.255.255.0
Until I changed the above entries the swap interfaces button was not present. (But was on DVD.)
Once I changed the entry, my network came back. So did the swap interface button, but then I no longer needed it.
Thought I should post a note.
If there is a condition on when the swap interfaces button should be presented, the condition should be removed.