I have just been bitten by this on a small business network with an inter-office VPN that needs to route through a separate router/gateway for about a month during a transition to a new ISP.

DHCP option 121 should allow devices to be pushed additional static routes. All Windows, Linux and Apple DHCP clients on the network work as expected but not Android-based devices, and I don't see an option on non-rooted devices to add the static route (not that I really want to do it manually).