You are getting a timeout while talking to 10.4.1.183 on port 162.
Are you sure that the Logstash machine can talk with this address? Also, why port 162 instead of 161?
You want Logstash to poll your snmp data, so you should use port 161 which is used for pulling the data.
It looks like a network issue, please try to run a snmpwalk on the logstash server to see if it is working.