I installed the tp-link ax1800 archer 21 at one of my office. Around 30*30 open space and at close distance speed was 700-800 mbps and throughout the office varied between 300-500 mbps.

what is your internet speed? both seem to be older models. In low cost routers, tp-link are generally very good. most have broadcom chips which is better than chinese mediatek chips.

its cable most likely. try another one.