Game wouldn't submit Grand Arena results

I just finished my grand arena match and won but when it went to submit results I got the cannot connect and bad internet. I'm on WiFi, I have just played a load of matches but this has happened quite a few times now.

I have put screenshots to show the situation and that my WiFi was stable. After restarting the game it says I have strong signal and there is no issue but I won't be able to win the arena match now.