Fix #DB2 Communication protocol failed to start issue: SQL5043N

I moved my DB2 installation to a new server from a full back-up. After performing all the necessary steps:
1. Recreate the necessary users: db2inst1, db2fenc1, db2das1
2. Give ownership to their home directories

ISSUE:
I tried to start the instance. I logged in to the db2inst1 user and started the database.
This was the result:

[db2inst1@localhost ~]$ db2start
SQL5043N  Support for one or more communications protocols failed to start successfully. However, core database manager functionality started successfully.

INVESTIGATION:
Looking at the reported issue with db2diag, the last entry looked like:

2017-11-21-11.59.09.811613+120 I313787813E494        LEVEL: Error
PID     : 14537                TID : 140148394157824 PROC : db2sysc
INSTANCE: db2inst1             NODE : 000
HOSTNAME: localhost.localdomain
EDUID   : 1                    EDUNAME: db2sysc
FUNCTION: DB2 UDB, common communication, sqlcctcpconnmgr, probe:5
MESSAGE : DIA3201E The service name "db2c_db2inst1" specified in the database 
          manager configuration file cannot be found in the TCP/IP services 
          file.

FIX:
The fix is to add an entry in /etc/services for the db2 TCP service

db2c_db2inst1 50000/tcp # DB2 connection service

Then just db2stop and try again:

[db2inst1@localhost ~]$ db2start
SQL1063N  DB2START processing was successful.