Unusable speeds on 2.4Ghz band

[wireless]

We have Telus 1gbps and recently moved and brought the router along with us. At our old location there was no issue, but in our new home the 2.4ghz band is extremely slow. I'm getting about 0-3mbps on my phone sitting next to the router using the speedtest app. On the 5ghz band I'm getting about 500-600mbps. I tried talking to a support but unfortunately they were unable to resolve it. Does anyone have ideas on how I can troubleshoot this?


More...