So I had these issues when the firmware first installed. It apparently failed on one of the nodes then it wouldn't connect and started acting all weird. I ended up factory resetting multiple times like you. Finally I setup up each node individually to make sure they were both updated to the...
If I'm understanding this correctly when you are connected to the router you do get 467, but sometimes it falls of to 200+. Same with WiFi. However when you are connected directly to the modem you are consistently getting 467 with no dropoffs into the low 200's?
If that's the case then...
That's odd. I'm assuming it has something to do with your settings then, do you have aiprotection turned on or any other services on?
I think you said this but you are sure your cable is a cat5e that goes from the modem to the router and a cat5e that goes from the router to your laptop?
Double NAT'ing just means you're behind 2 firewalls. This is usually a problem if you're using a modem/router combo. Do you know if the modem is a modem/router combo? If so then you'll need to place the modem/router in bridge mode and have your XT8 handle the firewall.
The XT8's should be able handle those speeds. If you're wired directly on the main node then you should be able to push that speed. If you're wireless and standing next to the main node you should still be able to get 400Mbps.
The XT8's have been buggy, hopefully firmware updates will fix...
I just bought the router about a month ago and had this exact issue. It would happen at midnight every single night and sometimes randomly throughout the day. I was on wired backhaul. This latest firmware update fixed that for me.