Write down the address you have. Go where you added the numbers, REMOVE, everything, and save it. Make sure only DHCP, and DNS is turned on. Turn off any options where your doing ANY of the 123.123.123.123 assignment. No subnet, no proxy, nothing.
Turn off everything using the network. EVERYTHING. Turn off the router, ALL of them. Wait... give it 5 min. Boot the router, WAIT 1-3 min boot the source WAIT, boot the Personal computers, WAIT.. until you can see the whole network via Network connection daisy chain. You will see what is booted, what is connected, everything.. It will tell if there is any issues..
If you need to access the actual router, you need the access 168.123. XXX.XXX usually. It will be in the router book. Best to access the router via ping at the command prompt.. If your not use to that. The Network daisy chain, might give you access, for a Factory reset to factory defaults..
Can you believe it. I was actually Novell and MS certified, a few year back.. Actually quite a few... Token ring, Novell, Unix, Fortain, pascal, C C++, Basic, Visual Basic, RGB System 36,38 and AS400 IBM..
Lucky if I could remember how to write a batch file for MSDos 3.0 or something worthless like that...
Opps, too much!!!
Excuse please
Best of luck...
Regards..