I have 2 PC's. They are connected via a swtich (router that is I think) and the switch also connects to an internet modem.

Both PC's have access to the internet, no problem. They are both set to get IP and DNS automatically.

Yesterday I set them up to both be members of the windows network (for printer and file sharing) "workgroup". And it worked.

I changed nothing, but today it doesn't work.

One of the PC's gets to "workgroup" fast and sees only himself there fast. (fast as in so fast it's suspicious).

The other computer takes a loooooong time to find "werkgroup" and then gets no access to open it. Even though I'm logged in as admin.

Anyone have a guess on what goes wrong and how to repair it? My feeling is that the former PC is OK, but the latter is not, and if it can access "workgroup" again, things will be fine.

I used to setup LAN's with manually set IP and DNS, but I guess the modem/switch needs them to be automatic and I certainly don't want to loose the internet connection.

btw the windows network is set up with the "windows locator" or what's it called option.

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both computers get the same subnetmask
IP starts with 81 but the rest is different
standard gateway starts with 81 but the rest is different

But anyway even if they can't see each other, each PC on its own should be able to access "workgroup", right? And this PC can't.

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This might be part of it. Your subnet mask is sort of a filter that has to be set up just right.

If your IP is 81.X.Y.Z, where x, y, and z are different for both, then your subnet mask will have to be 255.0.0.0. If your subnet is 255.255.255.0, then the first three numbers of the IP need to be the same as well. If the IP numbers are different, and the subnet is still 255.255.255.0, then you are basically telling the router that you have two networks.

The Gateway IP will only matter for the internet connection.

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OK, but if I set subnet manually, will internet still work?

I guess I can always try it out.

But still, it's strange that it won't allow me to even open workgroup and see my own PC here.

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ok what I did:

I let the computers get everything automatically and wrote it down.
I put in these values manually.
I changed subnet to 255.0.0.0.

Now both computers have access to the network and at least the problem computer can see both now (still working on the other one. edit: that one's fine too).

And both have internet.

Thanks for explaining how this subnet mask works.

I just hope that this continues to work in a few hours, when the modem would normally distribute new IP's...any thoughts on that?

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Yeah, that is odd that it can't see the wkgp on the local machine.

I've set up many computers here at the hotel with static (manual) IP configurations when the automatic ones didn't work. and we've managed to find the internet with just about all of them.

Pull up your LAN icon from by the clock, and select Status.
When that opens, select the support tab.
Now hit the details button and write down: The default gateway and both DNS Servers. These are the ones that will break your internet access.

If you do a manual configuration, keep the IP address the same for the first three octets (192.168.1.xxx, or whatever numbers your router gives out). Set the subnet to 255.255.255.0, then enter the gateway and DNS servers from above.

You may need to reboot to make it understand.

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Okay, then ignore the above.

For a static address, it won't matter.

The automatic function is called DHCP (as opposed to static). This means that who the computer is today is not necessarily who it was yesterday, or might be tomorrow. It's handy for networks with a very high number of users. For example:

Togco has 600 employees working 3 shifts, and they all need to access the network, so that's 200 per shift. With a subnet mask of 255.255.255.0, I can fit 255 computers on at once. With DHCP, I can set it to allow 250 automatic IP assignments, leaving 5 in reserve for the server and my PC, and a few printers. When the A shift logs on, their computers will find the DCHP server ans ask it who they are. It will tell them and all is good. When the B shift comes on, They can't all fit, but since most of the A shift is gone, the addresses they used will be put back in the system when they logged out, letting the B shift use the same addresses. The same thing will happen with the C shift. The catch is, the DCHP server doesn't know when the A shift logs off, so it doesn't have the current list of addresses. This is where the "Renew Lease" thing comes into it. If I set it to renew the lease every 8 hours, the server will try to ping each address it's assigned. If that address is still active, it will renew that address for another 8 hours. If the IP does not respond, the address goes back into the pool of available addresses. Since the one on my desk is a static address, the DHCP server never gave it out, and won't try to ping it to renew the lease.

Now, if I have 1200 employees, I'll need 400 IP addresses per shift. For this, I need to change my subnet mask to 255.255.255.0 I then assign A shift an IP of 192.168.XXX.xxx. This will allow me to have up to (255*255) or over 65,000 computers on the same subnet.

The main issue with a manual configuration is remembering what numbers are already out there. With 2 it's not that tough, with 65,000. it's better to let the machine do it.

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An evil person would do the things I think up.

So now the only chance of mishap is when my internet provider decides to automatically hand one of my computer's IP's to another customer (for a few hours at least) while my PC was off? That would make our internet fail for a few hours.

Doesn't matter, this situation is only for a few weeks, then it's just 1 PC here.

Thanks for your help!

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To the regular visitor of internet bulletin boards it is clear that it's an excellent idea your parents get to choose your real name.

Sure thing.

as for the first bit, that's where the Router/switch box itself comes in. If it's the thing on your desk handing out the numbers then you will never have a conflict with your provider. If the numbers you use are both from your provider, then it's not likely that you would be able to manually configure them at all.

My Home system has of IP of 67.something. This is the address of the modem and router. The router then assigns an IP address to all computers attached to it. My service provider can see my router, but they have no way to see how many computers are attached to it. (well, they probably do, but not in any way that would matter for this). If I turn off my computer, I don't give up my lease because it's the router that actually has it. If I turn off the router, I will get a new IP address from my ISP, but the IP's of the computers will be unaffected.

My one router at home can have dozens of connections (in theory), all of which show up as being from that same 67.something address.

Right now, I am at work and using my laptop. If the mods were to block this IP address, they wouldn't get the laptop, they'd get the hotel and I would not be able to post from any computer in the building. When I got home, I could still post from this same laptop, because the main IP assigned by my provider is different at home than it is at work. Now, if they block my work IP address, and it happens to be the same provider that is used by a private school in the area, it's possible that I might swap IPs with that school in the future, maybe after a power outage, and the school will end up blocked. This is just one of the reasons that IP blocking isn't something anyone really wants to rush into.

The only way you should run into problems is if the router connecting the two is not the source of the IP addresses.

__________________
I'm not evil.
An evil person would do the things I think up.

It is, so there shouldn't be a problem. nice.

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To the regular visitor of internet bulletin boards it is clear that it's an excellent idea your parents get to choose your real name.

Hmmm, now the reservation for the IP was over, and I lost the internet connection. i let it acquire a new automatic IP, and got back onto internet. Strange thing is that it was the same IP.

Anyway, I know how to solve things now when I need the network, so it's OK for a few days/weeks.

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Hmm... really odd. Maybe someone else can weigh in on it. I don't know why it might be doing that. My classes were of the "everything you need to know in 6 weeks" type though, and it was for Windows NT 4.0. TCP/IP should have changed that much, my 8 year old training might need some touching up.

__________________
I'm not evil.
An evil person would do the things I think up.

Don't put too much effort in it, with 1 minute of tweaking I will be able to make it do what it's supposed to do in the few weeks that I have 2 PC's.

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To the regular visitor of internet bulletin boards it is clear that it's an excellent idea your parents get to choose your real name.