slave stops replica

Hello,
I had master slave replica and yesterday the slave server's device was full on /var where the archive copy from master.  After trying to figure out why the pg_archivecleanup doesn't work, SA removed all wal files except the  current, August 25 wal files on slave and freed up /var with 504G available.  SA patched OS included reboot the server.  After the db started up after reboot, I found out that database/instance on slave is not sync with master.  The rows counted of queries containing these tables are not match with master from slave.
I tried to create a test table on master and didn't see it pick up from slave.  I found out again /var is full. 
What should I do to make slave streaming from master again without rebuilt the slave or must to rebuild it? Why my pg_archivecleanup is not working?  All the wal files stored since Nov 2020 ~ August 25.

Bach-Nga