Bot does not always send image

Node telegram bot does not send image to some users. I use the following code, which seems to be quite standard:

bot.onText(/text/, (msg, match) => {
  // From file path
  const chatID = msg.chat.id;
  const photo = `http://i.imgur.com/Hvr4CJX.png`;
  bot.sendPhoto(chatID, photo, {
    caption: "caption"
  });

Can it be some security thing, or that particular devices do not receive images, or maybe connection speed?

via Kristian Vybiral