when i connect through the ethernet cable i get a good speed but no through the wifi

we can try changing the channels on the router and for that , first we need to open the browser and login to the router settings page,either on the computer or cell phone.Select wireless,on the region menu select your region.From the menu , select a number from the channel menu,select 11 for 2G and select 157 for 5G.Now click on apply.

You can try to change the channels in the router :-

1. Launch a web browser & login into the router setting page from a computer or mobile device that is connected to your router's network.
2. Enter the user name and password. The user name is admin.
3. Select Wireless.
4. From the Region menu, select your region.
5. Select a number from the Channel menu, select 11 for the 2G and 157 for the 5G
6. Click the Apply button.