sure its normal, more masternodes in the network must share the same amount of blockreward.
Correct, but the other day they were 202 and now 165, so something is not right
Yes, it's not normal. But it happens because some nodes created wrong. They are announced in network but disappears after checking by other nodes.
The main error why they working wrong is closed port. Masternode ip:port must be reachable from internet.
I have made an protection from unworking nodes. Now staking wallet check masternode while adding it to list and wallet exclude bad masternodes from payment list.
Those masternodes never recieve reward.
As you said the port is the main issue, i have opened all ports in my windows firewall now, we will see if this work. Im still on 2.0.3.4