No I'm not sure. They have enough data connection where uploads and downloads happen correctly. I don't understand why Google photos pauses for a good minute before starts to upload to My Cloud.Sorry, but had to ask because from your picture it seems your signal is definitely not 4 bars... In any case, are any other downloads/uploads affected? Do you notice any slow browsing or data loading on other apps?
Best see, that's a good question. Since I have the old school plan I have unlimited and never try to over Wi-Fi but I guess as a test I could try. Try to remember to do that next time.Is it compressing pictures? Although I thought this was done in the cloud, though. Does it do the same while on WiFi or just on mobile data? Have you tried uninstalling/reinstalling the app?