DIAGNOSIS The router's hardware is capable, so this is almost always a configuration or device negotiation issue. Common culprits are band steering pushing devices to the wrong band, a congested channel, or a feature called 'Smart Connect' that's making poor decisions about which band your device should use.
FIX Log into the router. Go to Advanced > Wireless > Wireless Settings. For each band (2.4GHz, 5GHz, 6GHz), ensure the 'Mode' is set to its maximum capability (like '802.11ax/n/g/b' for 2.4G, '802.11ax/ac/n' for 5G). Disable 'Smart Connect' (which combines SSIDs) for now—give each band its own unique network name (e.g., MyNetwork_5G, MyNetwork_6E). Connect your test device directly to the 5GHz or 6GHz network explicitly.
IF THAT DIDN'T WORK Check for QoS (Quality of Service) settings under Advanced > QoS. If it's enabled, especially with bandwidth-intensive rules, it can throttle speeds. Try disabling it entirely to test. Also, in Advanced > System Tools > System Parameters, ensure 'NAT Boost' (hardware acceleration) is enabled.
HEADS UP Your internet speed test is only as fast as your internet plan. Test local transfer speeds (like moving a file between two computers on your Wi-Fi) to rule out an ISP issue. Also, some 'gaming' or 'security' features in the router, like VPN or built-in antivirus scanning, can add latency and reduce throughput.