Upgrade from 9.4.2 to 13

That big a leap will almost certainly require guidance from F5 and probably some intervening steps to one or more intermediate releases. If you can upgrade to v10.x, you may be able to leverage iHealth's Upgrade Advisor to provide some self-help guidance.

You have to go to a version 10.2.4 latest HF. Then you can go straight to version 13 but that is a huge leap. I would do something like 10.2.4 > 11.1.0 > 11.5.4 > 12.1.2 > 13.0.0. Other option which I prefer is to get a virtual edition with dev license and build the configuration in there in the version of your choice. Then you can upgrade your device to version 13.0.0 with no configuration and then copy the configuration from th virtual device. It is more work but for me is less risky.

I'd say go to version 12.1.2 HF1 unless you really need a feature in version 13.0.0. This version is not the most stable one and it has shorter support (around 18 months since March).