Guest network for IoT

I have router TP-LINK Archer C6 which doesn’t support VLAN. The good news is that at least Guest Network is supported.

  1. Is it possible and safe to put all IoT devices to Guest Network and using ‘Main Network’ for personal devices?
  2. Another way is that I could also plug in my old router into current Archer C6 and then maybe it will be correctly separated?

Sorry for newbie questions but I would like to start my adventure with HA safely.