Blynk offline error

I just worked with my project this afternoon.After I uploaded the script to my board,my project was offline even if the wifi was connected.The board do worked in the morining.What’s the matter?Is there anyone who can give me some advices?BTW my board is Nodemcu v3.

how about providing your sketch so we can help ?

Oh,I’m sorry for replying so late.The board was able to connect to my wifi and worked just now.I think wifi condition may be the factor when I post this topic.