SECONDARY member of mongodb replica set is not match with PRIMARY

I'm using mongodb replica set with two data center.

One day, because of unknown packet drop, replica set was broken.

So I restored replica set by removing/adding secoday , but It still something wrong

Here is rs.status(), rs.conf()

Why last heart beat is too old?

Replication with two mongodb is not working

for example, total count of collection 'letter' is different to eacth other

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