Diagnosis
This is almost always a device or configuration issue, not the router being slow. Common culprits are older client devices, incorrect band selection, or a suboptimal channel.
How to Fix It
First, identify which band you're connected to. In the Tether app, check your connected devices—see if your phone/laptop is on the 2.4 GHz network. If it is, that's your problem. Forget the network on your device and reconnect, making sure to select the 6 GHz or 5 GHz network (named with _6G or _5G). Second, run a speed test with a device wired directly to the router via Ethernet to rule out an ISP problem.
If That Didn't Work
Interference or a crowded channel can cripple speed. In the router's web interface (Advanced > Wireless), try changing the 'Channel Width' for the 5 GHz band to 160 MHz and set the 'Channel' to something like 36, 40, 44, or 48 (these are typically clean). For 6 GHz, leave it on auto.
Heads Up
To get true Wi-Fi 7 multi-gigabit speeds, you need a Wi-Fi 7 client device, be connected to the 6 GHz band, and have a modem/internet plan that's faster than 1 gigabit. Otherwise, you're capped by the slowest link in the chain.