3 Macs on router, one wont hook up now

[jcarter]

We have ethernet, and never had a problem with our 3 Macs, but yesterday my husband got this alert,
"IP Configuration
192.168.1.6 in use by
e8:06:88:57:e1:44  DHCP
server 192.168.1.1"

He clicked the OK button yesterday and then his computer would hook up fine.
But today, nothing, Ive restarted, and switched holes in the router with one of my Macs, which are still hooking up fine.

I didnt restart the router or the cable modem, as they wouldnt be the problem since both of mine are OK.

On the network prefs, I see that Configure IPv4 says 192.168.1.5 for one of my Macs, and the other one is .3 so where is this .6 coming from on his?
But I dont know beans about networking,,,,,,,
I wonder if its the cable itself, its about 25 feet long, but the cat has never gotten to it, as it goes up along the ceiling.

But I sure will learn.
Thanks,
Jane

[jcarter]

Went to the store, came back, changed the router plugs back the way they were, and the alert box came up.
But when he clicked OK, it connected to the net again.
Strange, but I would love to find out what is going on.
Odd, isnt it.

[Xairbusdriver]

"e8:06:88:57:e1:44" is simply the MAC address for the machine that has been assigned the 192.168.1.6 address. The Media Access Control address is simply a (unique) number assigned every piece of hardware that might ever be used on a network. The 192.168.1.x is what the Internet sees as the Mac's IP address. It is usually assigned by the router via DHCP.

I suspect that at some time, there were several computers connected to your router (yours, kids, friends). When your husband turned his Mac on, it was assigned the .6 number. Usually, the router will assign whatever numbers are needed, starting at .1. But it may be still trying to assign the .6 to your husband's Mac.

I assume your Network Prefs shows "Configure IPv4: Using DHCP".

Here's what I'd try:
1. Turn off ALL computers.
2. Turn off the router and the cable modem.
3. Wait 5 minutes and 23 seconds.
4. Turn the cable modem ON.
5. Wait 3 minutes and 48 seconds or until all the lights are normal, whichever comes last.
6. Turn the router ON.
7. Wait 4 minutes and 12 seconds or until any display lights are normal, whichever comes first.
8. Turn ON your computer.
9. Check that it is connected to the LAN and you have access to the web.
10. Turn ON your husband's computer. Repeat step 9.
11. Turn ON any other computers, one at a time, repeating step 9 with each.

[jcarter]

Thank you!
It works fine now, I really dont know why this happened yesterday, and once the day before.  
Actually all 3 computers are always connected, unless my husband turns his off at night, I leave mine on and connected.
Each of the network prefs do show "Configure IPv4: Using DHCP".
Sometimes we have the grandkids iPads and iPods using the wifi along with the kids smartphones and other laptops, so I guess thats a whole lot of things connected.
But there is never trouble then or on the weekends, it was just a weekday.

My husband just turned his Mac on, and not a problem, no Alert message, hooked up an a microsecond.
Very very odd. But I have saved your info, and if it happens again, I will follow your instructions.
Wonder if it had someting about our power being off for 4 days, and cable and phone was also out.
My husband said NOT to run the computers when our generator is on, even tho I have our UPS things. As if it runs out of gas or the freezer or well water pump comes on, the thing lugs down and the power dims a bit.
Jane

[Sasha]

LOL. Those instructions are just about verbatim the ones that our satellite provider (wouldn't if we didn't have to) suggests for every time our dish/modem drops its signal, which for a while was three and four times a day. It really is the router either dropping an address or failing to pick one up, and the aforementioned reset will do the trick.

[jcarter]

I have had to do this in the past when our cable provider went messy, but that was a long time ago.

In this situation, since all other computers in the house were working fine, we just waited, and the next morning everything was fine.
So what you mentioned about the router having a hiccup, was probably it. Changing 2 of the cables could have done it too, as I did do that.
And the puppy did get under the desk a couple of times, so that could perhaps meant one of the cables getting yanked upon.

But its all OK now, mysterious.

Next project is to fix the 4wd on our truck,,,,,,,,,

Thanks,
Jane