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RogerSawkins
Occasional Contributor
Occasional Contributor

Sagemcom F@ST 3864AC WiFi device ip addresses not static

Each time I turn on the modem, it sets a new IP address for each of my computers ("devices"). For example, it will set my primary laptop as 192.168.0.3 on one occasion and 192.168.0.5 on another. This means my Windows 10 network won't work reliably.

 

How do I specify static IP addresses for each device?

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petergdownload
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

The modem has a DHCP server (that gives out IP addresses to all connected devices). You can see it in the menu settings of the modem. It will show a IP range you can set eg:

 

192.168.0.1 - 192.168.0.255

 

First up change that range to something a bit out of the way eg:

 

192.168.0.210 - 192.168.0.240

 

This will mean that any devices getting automatic IP addresses will get them in this range. The purpose of doing this is you don't want the automatic addresses to conflict with any static addresses.

 

That's the modem done. The next step is device specific. On each device you have there will be Network settings and you probably have them set to something like USE DHCP, AUTOMATIC, etc. Simply change the settings on this device to be static. You will need to set

 

IP ADDRESS - the address you want the device to always have (192.168.0.3? etc)

IP MASK - usually 255.255.255.0

GATEWAY - your modem address (192.168.0.1?)

DNS - your modem address (192.168.0.1?)

 

Peter Gillespie

 

PS There's also a way in most DHCP modems to assign a specific IP address to a specific device MAC address, but that's probably more complicated than you need.

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RogerSawkins
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

I am familiar with setting each device to a specific IP address, through the "hosts" option.

 

I have not yet altered the modem as you suggest as I don't see how it will ensure that all devices get the same IP address when they are each booted up (I have four altogether). If I boot them A, B, C, D won't they get different IP addresses than if I boot them D, C, B, A? And what of the device (printer) that is set on 192.168.0.6?

 

Roger

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petergdownload
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

"hosts" seems to be overly technical.

 

Setting a static address simply means assiging the IP address you want a device to have on that device. That way there is no A,B,C or D, just a device with a fixed (static) IP address. For example on your PC you presumably have it set to obtain an IP address automatically in Network Settings, you want to switch it over to manual (static):

 

sshot-20.jpg

 

The DHCP server (on your modem) is used to give out random IP addresses to devices that don't need to be static. Just reduce the range given out as otherwise it will give out the same address to a device that you might have set fixed on another device.

 

Peter Gillespie

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RogerSawkins
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

A long and tedious process with four computers, but it seems I have set them up and all are now on fixed addresses (and my printer still works).

 

That solves that problem, but now I have to go back to Microsoft to get their Network system to work properly. They abolished Homegroups on the latest upgrade with no warning and no help with resetting networks and so I have had to have a similar conversation with their help people to reset all the computers on the network.

 

Such a friendly mob, aren't they!?

 

Thanks for your help.

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petergdownload
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

Tedious Networking is a Tuatology Smiley Happy Did you know that at the dawn of time (around 1980) bigger firms had people whose sole job was to update the hosts file IP addresses, so that all the company PCs could keep talking to all the other PCs. Its all they did all day apparently.

 

You should be right now, however there is another method that retains the PC on DHCP (auto IP) called Static DHCP. Not sure if the Optus modem offers it. Essentially in the DHCP section you can enter specific IP addresses and force the server to assign a specific address to that machine. looks something like this

 

Good luck with the Home Groups.

 

Peter Gillespie

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RogerSawkins
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

I finally found a way to fix static IP addresses on the modem - not on each computer.

 

First find the computer's MAC address by hitting the Windows key, type cmd [Enter] and then ipconfig /all [Enter].

Under "Wireless LAN Adaptor WiFi" the "Physical address" is the MAC address of that computer.

But, convert the address from what it shows 1C-4B-D6-92-F6-6K to 1C:4B:D6:92:F6:6K (i.e. replace dashes with colons).

 

Log in to the modem and go to "Advanced Setup". Change the "Start IP address" (at the bottom) to a higher figure out of the way (50?)

Underneath that click "Add entries" and put in the MAC address and the preferred (static) IP address (say 3).

 

Do that for each computer. Restart in all directions, and presto! you have a fixed IP address for each computer and the network is stable.

 

I found that not all computers will show in the Network window of Windows Explorer, but they can be found by putting the computer name (e.g. \\Laptop) in the address bar. Another alternative is to construct a short cut on the desktop or elsewhere. Software on one computer can also open a file on another computer that way.

 

(I also had advice to simply "leave the modem on 24/7" - hardly an environmentally-friendly or cost-friendly solution!)

 

I still find it unbelievable that Microsoft can just abolish the Homegroups and leave everyone with days of investigation to get a stable network.

 

Real black mark, MS.

Dan_C
Retired Employee
Retired Employee

Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

Ah, really good info @RogerSawkins

 

I'm sure that'll come in handy! 

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Kabe
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

Thanks Roger for your heads up. A question re your suggestion to get static IP addresses on the Sagemcom.

 

OK, change the "Start IP address", did that to 192.168.0.50 as you hinted, then went "Add entries" and confused (easily I know) by your comment (say 3) ???? What do you mean by this?

 

The Sagemcon runs 24/7 but each time the two laptops, an iPad and a Raspberry Pi, which connect by WiFi are turned on, they are given a new IP address. A pain in the colon (pardon the pun).

 

TIA.

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RogerSawkins
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Re: Sagemcom F@ST 3864AC WiFi device ip addresses not static

Yes, I was using shorthand! Under the start IP address, etc. is the "Add entries" which will bring up a screen asking for the MAC address and the IP address. What I meant by "the preferred (static) IP address (say 3)" was put in 192.168.0.3 or whatever address you prefer for that computer. Similarly, other computers can be 192.168.0.4, etc.

 

Increasing the Start address simply stops the modem from allocating those addresses to some other piece of equipment (e.g. a printer) before you turn on the computers. We have a modem which starts when we turn on the computers so it is not on 24/7 but that shouldn't make any difference.

 

I am on Windows 10 but I assume all this applies to Apple machines as well.

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