Here are a few things to try:
1. Changing the channel number in the router sometimes helps with connection and speed problems. Change it by a factor of 6, e.g. if it’s currently 11 make it 5 or if it’s currently 1 make it 7.
2. Move the router to find out if nearby electrical or radio activity or something metallic is causing interference.
3. Delete the wireless connection and set it up again.