Also can disable mixed mode (b+g) unless you still have an old "b" device. This has some choke.

the interference of channels is a big probability. Do a survey of your house and see if your channel is being used by the neighbors. Pick the one w/ least signal strength from others.

Use only channels 1,6&11 on 2.4GHz. If one of your neighbors is being a channel hog, go turn off their house main breaker .

These are the initial ideas that come up. There are more down in the weeds tricks to try.

Z