Cash only sign suddenly appearing?

[SCA_Fashion]

Hi. This is a new one. A cash only notification appearing even though the internet is fully working and we are taking payments by card as normal? 

 

[Bronze_Palms]

Mine did this the other day as well! I find that if my connection is spoty it will do this, if I am on hotspot for the ipad, or the ipad is about to die.