RAX35 Guest network seeing main network

I love this router but would like a change in the firmware.  Whoever thought it was a bright Idea to allow Guest to see the main network did not think this thru.  The main pupose is to seperate the 2 networks.  I use my Guest Network for all my IOT devices.  Your old routers use to do this.  I could tell it to allow each guest to see each other or not.  Now its Not see each other or see each other and My main network.  Really?????  What if I have a guest printer?  Now I can't share it on guest as no one can see it.  This makes no sense to me at all.  Please make changes to the firmware so I can keep them seperated all together.  Otherwise whats the point?  Thanks,

Kraig