After connecting a mac mini to my network my macbook pro can't find back-up drive

Hi - I am a reasonably long-time mac user - but not particularly competent at fixing network issues.

I have a macbook pro, a new mac mini, a Netgear WNDR 3800 router and 2 WD MybookWorld 2 hard drives.

All was working well - my macbook pro could back-up using time machine to one NAS drive and I saved my music on the other NAS drive. I then connected a new Mac Mini (via ethernet). When that is switched on the macbook pro can no longer see the back-up drive. When switched off it can.

I have also noticed that my macbook pro has a tendency to drop the wireless signal for seemingly no reason.

Clearly the mac mini is interfering somehow with the network - but no idea how. Google searched the issue and strangely can't find any examples of people with the same issue - which is unusual.

Any help greatly appreciated.

I'd suggest that one or more of your devices has a self-assigned static IP address and that's the clash that's causing the issue.

As for rectifying the issue that all depends on whether any of your devices NEED a static IP.

The best thing to try initially is to ensure that all your devices get their IP addresses from the router via DHCP. (i.e. set your network setting on the Macs to automatic and go into the settings on the world books and set those to auto/DHCP)

If you have a need for a device to have the same IP on the network all the time you can use the Lan IP setup on your Netgear router to always allocate the same IP to a particular device. That way the router is still in control and all devices still receive IP address from the router by DHCP.

I did consider that option. However, I have never set a static IP address for any of them and checked on the router and they all appear to have been issued separate IP addresses.

The reason for the delay in replying is that suddenly everything started working (no change in set-up). However, yesterday the same problem reoccurred. I now have the Mac mini backing up the drive I saved my music on. At the moment either computer can back-up provided the other computer is switched off.

It is weird that this has become an intermittant fault. I suspect that the issue may not be the network and something to do with the worldbooks set-up.

Any other thoughts greatly appreciated.