Overlapping Subnets - Forticlient works on PC, works on Android, doesn't work on iOS

I am seeking help with a problem that I cannot understand. One of our staff members has a subnet at home that matches our subnet at work, being 192.168.0.x/24.

Normally I would dismiss this out of hand as likely to cause routing problems and so forth. This user is a QA person and therefore uses a PC, Android device, and iOS device as part of her workflow, to connect to resources in our corporate network.

Using Forticlient on each of these devices, the PC works (despite the overlapping subnet), Android works (depite the overlapping subnet), but iOS does not work.

In the iOS case it is not using the corporate DNS and it is not routing traffic to the corporate LAN.

I know the usual recommendation is to renumber the corporate subnet, but I am also reticent to do that because it is ultimately just a symptomatic fix until we get another conflict.

Any ideas on how to troubleshoot or what settings might be available to assist. We have split tunnelling enabled for VPN users. I tried setting up a different VPN portal for this user and turned off split tunnelling, but that resulted in none of her devices being able to route traffic (although this could be a misconfiguration error on my part).