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Do you access steemit on workplace or home? If suspect this could be due to firewall or proxy settings at your work or office network.

Exactly. This seems like a network problem more than Steemit or Steem+.

I access steemit only on my phone. And I don't think I have made any settings for firewall protection. It temporarily subsides if I restart my phone

As @techstack says, it seems to be a network issue