Seems situation is normalized again.
At least all three of my nodes are synchronized, the blocks are coming up correctly and I can mine again.
But it's very bad that more than 50% of the network is in the hands of one miner and it can generate 5 blocks in less than a minute.
It's not just bad, it's terrible

. Makes the whole of point mining this coin worthless.
It is the pool, i guess. You have to use the fast miner and this miner is very fast, compared to the original one, developed by the dev.