Unable to connect to host: Please check Networker Security setting and daemon logs on the networker client and Console server for more details: Unable to determine the name of address

trying to create a backup set, selecting the target drives or folders I get this error. I have the 8.1 version of networker

Ah, you are using wizard.  In that case I suspect that either servers file is not set correct or nsrauth/NSR peer is not set rights.  To avoid too much mumbo jumbo as you say this is urgent, simply create client manually (if this is new client) or copy existing one where you would change:

a) save set value to path which you wish to backup

b) group value to group that you want

c) any other parameter which may apply (like browse/retention policy or/and schedule).

Actually, I'm talking rubbish... error seems to suggest that server can't resolve the name you used for client as it seems... are you sure name can be resolved on backup server?

Seems like a reverse name lookup issue. A given ip cannot be resolved to a name.

Since a while NW insists of the fundamental issues to avoid other problems.

So make sure that the name resolution works forward and reverse.

BTW - I don't know why but from time to I experience reverse lookup issues sporadically on some clients.

A reverse DNS entry always helped to solve this.