Can't configure FastEthernet interface

It is not Fastethernet, it's ethernet.

Try "interface EthernetX"

The 4 Fastethernet  switch ports are L2,  it's unlikely that you will be able to do anything on them, they are provided to do switch/hub functionality since this is SOHO router from cisco.......

If you give command "interface ?", this will show you the list of configurable interfaces and Fastethernets will not be there.

Best,

what do you mean they dont work?

how do you know this - is the user getting pop ups telling them that services cant start?  or are you just seeing the event viewer entries?

Its not exactly clear what your trying to do.

If I remember correctly the ports are named
FastEthernet0-3 which are all L2 ports and don't support much on the 837. So there is no 5th (FastEthernet4) port

Ethernet 0 is a layer 3 port connected to the switch.

there are some firmwares avilable for the 837 which will turn FE3 into a vlan'ed port and create a Ethernet 2 which it is then bound too and cannot be used as a 4 port switch anymore. Its a 3 Port + 1 Port switch :) But i can tell you don't have one of these firmwares installed.

I'll try to explain better the situation.
I have a Router Cisco 837 with 4 ethernet interfaces, like this:
http://www.cisco.com/en/US/docs/routers/access/800/837/hardware/quick/guide/837qsg.html 
As you can see above, the router's requirements are:
1. ROM: C837 Software (C837-K9O3SY6-M), Version 12.2(13)ZH4, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)  
2. System image file is "flash:c837-k9o3sy6-mz.122-13.ZH4.bin"
3. 32 MByte DRAM
4. 12 Mbyte Flash memory
In this paper:
http://www-europe.cisco.com/en/US/products/hw/routers/ps380/prod_bulletin09186a00801c437a.html
Cisco declares that the function 'Managed LAN Switch': Supported platforms: Cisco 831, 836 and 837; supported in all images (all k9o3y6 images).
My router Cisco 837 has loaded  k9o3sy6-mz.122-13.ZH4 image, so the function 'Managed LAN Switch' should be integrated, but if I type 'show interfaces' I see only ATM0 and Ethernet0 interfaces.
The same error appears when I typed:

Router#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#interface Ethernet1
                                                      ^
% Invalid input detected at '^' marker.

or

Router#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#interface FastEthernet1
                                        ^
% Invalid input detected at '^' marker.

On Internet there are too many examples of Cisco 837 configurations, where there are 4 FastEthernet interfaces, I found an example here:
https://www.experts-exchange.com/questions/21882721/Setup-VPN-using-Cisco-837-router-adn-Pix-501-Firewall.html 

Now the questions are:
1. Does anyone know why the router Cisco 837 has this behavior?
2. Does anyone know what is the Cisco IOS version where the function 'Managed LAN Switch' really is implemented.
3. Must I reloaded a new image of 'c837-k9o3sy6-mz.122-13.ZH4.bin' and where do I find that.

Kindly regards.
Antonio Morrocchesi

Ok,

The 837 wont do what your wanting. It doesn't really have the hardware power to do it.
The next set of router that will do it is the 87x series. The 85x series also might do it.

With a standard ios you get 2 vlan's of your choice.
With the advanced ip ios you get 4 vlan's

The 83x series only offers 1 Ethernet Layer 3 Port and 4 Fast Ethernet Layer 2 ports (partially)
So it isn't really a managed switch but you can tell what state the interface is in.

FastEthernet0-3 are all Layer 2 ports , meaning that you cant assign a separate IP to each one. You can assign vlans (if you use specific IOS)

You will assign IP to "Ethernet 0" ; its similar to "vlan 1" in newer cisco models , like cisco 87x series.

amprant: the 837 does not support vlan's

It supports with specific IOS , from Y series

The router gets 32 MByte of DRAM and 12 MByte of Flash memory.
Does IOS Y series support this requirements?
I know that Cisco doesn't support the 837 series, Where do I find Y series IOS on Internet?
Kindly Regards.

Antonio Morrocchesi
 

I assume it is the same issue as with the PIX501. The built in switch is not realy configurable. Just couldn't find a note from cisco explaining that.

Perhaps you find what you are looking for here:
http://www.velocityreviews.com/forums/t41820-cisco-837-configuration-issue.html