I just got my AX20 Archer AX1800 today (Hardware Version: Archer AX20 v1.20, and Firmware is up to date) but when I use the Ethernet using Cat 6 cable it only gives me around 250 Mbps where my full speed from my Fiber plan is 1 Gbps.
That's not even 30% of the full speed!!!
Also, wireless connection using iPhone 11 PRO gives me higher speed than wired connection but still not even 40% of the full speed.
I got around 300 Mbps using the iPhone 11 pro with:
Channel Width: 80 HMz (the highest)
Mode: 802.11a/n/ac/ax Mixed
Internet Connection Type: Dynamic IP.
Internet Port Negotiation Speed Setting: 1000Mbps Full Duplex.
Both wired and wireless speed are way slower than they should!