youtube videos constantly buffering / won’t play

[grasshopper1]

so i’ve had the wifi for about 2 months now everything was working fine till about a week ago videos on youtube won’t play or constantly stop and buffer i’ve seen 2 other posts about the same issue with no solution so i’m certain it’s not just me i’ve phoned customer service all they say is restart your router or call out an engineer for £40 everything else works fine it just seems to be youtube that’s not working properly 

[NigelB72]

If you're using YouTube via an app, try deleting the cache... If that's full, it will cause buffering issues as it can't store the required data. 

It should automatically clear but sometimes it doesn't....