#!/bin/bash
s="some.dns.com
up 720 days,
some version
several lines of disk space information, between 14 and 16 lines
Connection to 10.1.1.1 closed.
 
some.other.dns
up 132 days,
some version
several lines of disk space information, between 14 and 16 lines
and more lines here
and here
Connection to 10.1.1.2 closed."
 
awk -F"\n" -v RS="" '$0 ~ /up (9[0-9]|[0-9]{3,}) days/{gsub(/Connection to | closed\./, "", $NF); print $1 "\n" $NF}' <<< "$s"

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