Huawei Mediapad 7 youth s7-701u too slow wifi connection issue topic

hi , my tablet wifi connection speed extremely slow. i have 16mbit connection speed. My laptop connection is smooth. at tablet when click to link usually connection times out or waiting too much. tablet wifi bar is full. i checked wifi signal power from tablet menu, show signal -100dbm around. İ guess it is low power signal.maybe this problem because of it. this issue appear after downgrade tablet rom and reset my router. i dont remember how i solved. please help.