Client complaining WiFi is ‘glitchy’

Attached are photos of a client site. It is a residence approx 4200sqft. Their primary complaint is WiFi feels a bit slow at times, leading to YouTube buffering and whatnot. When I look on the backend everything seems perfectly fine, except a low percentage of tx retries. What do yall think might be the issue?

6gh disabled last night to keep signal strengths high.

Edit: how do I add photos?? Grr
DNS has been updated per recommendation to Googles exclusively.

I think the culprit maybe that one of the APs, a U7 Outdoor is connecting at E rather than GbE. Time to replace a short cable…