Hi Nikos,
Since there is no configuration migration when you move from 9.2 to 9.1. So you can downgrade the device by changing the boot variable itself. It is better you upgrade the device to 9.1.6.11 where the ike vulnerability issue is resolved since there are some critical bugs in 9.1.7. Or else you can upgrade the device to 9.2.4.5 where the ike issue is resolved.
Please note that these releases are interim.
Thanks,
Shivapramod M
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