Hi Katala,
A bit of an update on this. I spoke with our engineering team and it’s my understanding that if there are no available mesh gateways on the network, the network should try to promote any available gateways on the network.
I’ve personally not tested this configuration much, but do recommend you give it a shot and share the results here with us. You should be able to re-add your Argon to the existing mesh network through following these Mesh over USB setup instructions for adding a Node to your network here. Though the instructions are for a Xenon, they can be followed for your Argon as well.