If I had to guess, my best hunch would be that your block files is corrupted. You have to scour your debug.log file abit more and see if anything indicates that the blocks are corrupted.

I highly doubt that it's your internet being restricted. But to eliminate the possibility, you'll have to see when was the last line that Bitcoin Core synchronized. Did you have any power outage or any time when Core had an unclean shutdown (abruptly).