Hi LBM
Sorry to hear you are having issues with this. The Guest Wifi is still a fairly new product and currently does have it's limits, so it may not be suitable enough to meet your needs - however I would recommend contacting our help and support team here to discuss this further. I would not know much in regards to third party routers, and neither would that team - but they can give you more info in regards to the Hub 6 at least. It may be the case that you are more suitable on a thurd party router as ours are designed for basic use and any special configuration may not be possible.
I hope we can help you find a suitable solution for this one!
Regards
Ryan