Found is supplier issue, they connect my internet to exchange tower too very far area. Decided to change the supplier now. Thank you. But after changing the router, it did improve only a little bit not too much,. Thank you for everyone's help.
If do not purchase it, Supplier will say that is your router issue. At end, they tell me the truth, they connect us to very far place.......However, thank you for your help and advise.