NEW UPDATE - I don't know what exactly happened, but when I set up the IP range to 192.168.1.1 - 243, I started getting speed test results of 820/43, which is MUCH better! Perhaps it took a while for the signal to settle in? I dunno, but I'm happy with it now, though it took far too much wrangling to get the expected result. 

ORIGINAL POST:

My Archer AX11000 was delivered today, 2 days after I installed my ASUS PCE-AX58BT (AX3000 Dual Band PCI-E WiFi 6 (802.11ax) Adapter with 2 external antennas. Supporting 160MHz, Bluetooth 5.0, WPA3 network security, OFDMA and MU-MIMO). The AX11000 is connected to a 1000/40 Fibre to the Home connection, and the internal speed test from the router to my ISP is as expected, at 920/33, about the same as my old router. 

However, actual WiFi test results have been... disappointing.

On my old Belkin WRT32X 802.11ac w/ Intel AC 9560 WiFi card, I would get approx 560/43 when using my ISP's speed test. AU$900 later, and I'm getting a whopping 550/42, which isn't quite the Gigabit speed I was expecting. In fact, it's even SLOWER than my old WiFi network!

I've manually changed the 5GHz channels to a DFS channel of 52 for 5GHz-1, and 116 for 5GHz-2. Both are set to MU-MIMO enabled, while the 5GHz-2 is set to 802.11ax only, 160MHz Channel width and High Transmit power (this is the primary connection I'm testing on). I've also forced 160MHz on the Asus NIC. You can see all my settings here:

https://drive.google.com/drive/folders/1vUCqTqX6Ocu2_e9wJ0tNNegGtZuya7nm?usp=sharing

Note that the Router is approximately 8 meters away from the PC, with a single concrete slab and one plaster wall between the two. While the WRT32X delivered a signal strength of -47dB, the new AX11000 only gives me -60dB!!!! (measured using Galaxy S20 Ultra w/  WiFi analyser app). The channel is well away from any others. 

I'm rather unhappy about this. Any ideas would be appreciated, otherwise I'm returning this for a better router. 

UPDATE - I fixed the IP stuff. Speed still terrible. Damn, this is an ugly interface! Hate how the peppering of the word gaming throughout just confuses stuff.