Reccomendation for WLAN failover

[fireix]

Hi.

I have a secondary private network (for camera, ipmi, power management etc), with private/local ips connected to a layer2 switch.

For the most part, I administer this through a management computer that has a public IP on one interface, and the private IP (and DHCP-server activated) on the second interface.

Now, to have another way into my secondary management computer, I have a 4G modem (router) with public static IP as well (different ISP/vendor), connected to the same switch/private network above.

This causes a bit of a headacke for me. If I access management computer over my cabled network, I need to have the DHCP-server to give out IP and gw to this management computer in order to work. If I access the network through 4G, I have to set the gw on all devices/DHCP to the 4G router.

Someone suggested that a switch with failover-WAN would be the solution. I would just replace my private switch with a bit more advanced one. This switch should then also manage DHCP and I should set the DHCP to give out leases with the IP of the switch.

1. Is this a 100% solution and would it work as planned above? How would I configure the two sources? The 4G router has NAT (through what they call virtual server) so I must assign this somehow.

2. Example of what this is called when I'm looking to buy. 1U switch.