10.230.146.10:   Terminal ID        Gol
10.230.146.10:   Far End ID            pol
10.230.146.10:   Number of E1s     4E1s
10.230.146.10:    Packet link capacity  63Mbit/s

10.230.146.10.  Terminal ID.  Far End ID.  Number of E1s.   Packet link Capacity
Gol.      Pol.    4E1.     63Mbit/s

awk '{if($1 == ip) {$1=""; printf "%s ", $0} else {ip=$1; printf "n%s ", $0;}}' input.txt

10.230.146.10: A B
10.230.146.10: C D
10.230.146.11: E F
10.230.146.11: G H

10.230.146.10: A B  C D
10.230.146.11: E F  G H