Sounds strange but when i try to buy an app in Play Store, very often, about 80%, i get a "Error Connection timed out." message. Ive also noticed that the wifi icon was greyed out for a short time when that happened.
Same problem when i try to download a tomtom map with 1 gig, at the beginning i get about 1,3 MB/sec, after a minute it drops to 50 KB/sec, so i checked the network details. Signal strength stays at excellent, but link speed drops from 390 Mbps to 6 Mbps without any reason.