Ubuntu Server on Edge Gateway 3002

Hello everyone.

I'm currently trying to upgrade the OS in an Edge Gateway 3002 and I haven't had much success up to this point. The gateway came with Ubuntu Core 16 but I'd need to install Ubuntu Server 18.

Ubuntu Server is actually an option in the Dell Store during the gateway configuration phase, but I can't seem to find any reference in the manual on how to install a new OS on an already existing gateway.

Could anyone point me in the right direction? Any help would me much appreciated.

Thanks!