If you want to avoid having a single gateway server – thus risking a single point failure -, 

you can activate the gateway portal and load balancing on a second server – to provide a failover to your farm -.

All you have to do is replicate your load balancing configuration on your second server.

Once it’s done, you may either provide: 

– the alternate URL to your users,

– and/or generate a new connection client that points to the new gateway.