Gigabit internet shows up as 400Mbps

JoelM3d  I understood what you wrote. Speeds of 200 to 400 Mbps are as expected.  The achievable WiFi speedsactually has nothing to do with your Internet connection speed.

1. The 866 Mbps link rate means this is the MAXIMUM rate that the router and a client can exchange data.  This rate is only achieved under ideal conditions, such as in the same room, no obstructions between devices, and with no sources of interference.  This rate is not achieved through walls, etc.  The rate also adjusts constantly with time, and will be different for communications from the router to the client, and from the client to the router. The connection from the client to the router is often less, especially with a phone, which has weak radio, poor antenna, and is blocked by your hand.  This is why uploads can be less. As I wrote earlier, the expected THROUGHPUT is no more than 50% to 60% of the link rate, so the maximum you should ever see is 430 to 520 Mbps on 5 GHz and 200 to 240 on 2.4 GHz. This is because WiFi has a lot of management traffic that eats up the link rate.  So, your WiFi results of 200 to 400 are in the normal range.

2. If you want to test and optimize your WiFi performance, then you should use a proper tool like iperf3.  Download a copy of iperf3, run iperf3 as a server on a desktop or laptop wired to the router, and run iperf3 as a client on a WiFi laptop.  On my iPhone 7+ connected to the Orbi router, I measure between 385 and 520 Mbps using iperf3 to a wired server connected to the Orbi router. I wouldn't use the Orbi speedtest or pay much attention to, as it's not measuring speed through the Orbi to your clients.

In your latest post you said you were only getting around 40 Mbps.  That is lower than expected. Yes, I would try a reset.  You might have other devices in the home causing interference though, such as neighbors' routers, wireless speakers, etc.