Cisco 1841 and Starlink - need help

[rspears1966]

First I know the c1841 is 10/100 only.  Starlink has a GigE uplink, but still, will it work?

I'm not asking for a theoretical answer, I know theoretically it should work, I want to know will it work?

I have put this config (see below) on mine and tested the NAT, it works.  I see the router grab a Starlink CGNAT IPv4 address.  But it will not pass traffic.  I can ping the WAN interface Fast0/0 from inside the network, but I can not ping past.  Also, when I try to do a source ping (4.2.2.2) from the WAN interface, it fails to respond.  I can drop my Cradlepoint in place, and it works flawlessly, so I know it's not any of the cables or the Starlink equipment. 

I am using c1841-advsecurityk9-mz.151-3.T2

Advise please.

c1841#

ip cef

!

interface FastEthernet0/0

ip address dhcp

ip nat outside

ip virtual-reassembly

duplex full

speed 100

no cdp

!

interface FastEthernet0/1

ip address 192.168.0.1 255.255.255.0

ip nat inside

ip virtual-reassembly

!

ip forward-protocol nd

!

no ip http server

no ip http secure-server

!

ip nat inside source list 100 interface FastEtherner0/0 overload

!

ip access-list extended 100 permit any any

!

ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 

!




c1841#

[Georg Pauwen · Accepted solution]

Hello,

the access list used for NAT does not look right. Make the changes marked in bold:

ip cef
!
interface FastEthernet0/0
ip address dhcp
ip nat outside
ip virtual-reassembly
duplex full
speed 100
no cdp
!
interface FastEthernet0/1
ip address 192.168.0.1 255.255.255.0
ip nat inside
ip virtual-reassembly
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
--> ip nat inside source list 1 interface FastEtherner0/0 overload
!
--> access-list 1 permit 192.168.0.0 0.0.0.255
!
--> ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 dhcp
!
c1841

[rspears1966]

I will give this a try tonight, and update this thread.

Thanks in advance !!!

[rspears1966]

That did the trick.

Updating the config to reflect these changes worked.

--> ip nat inside source list 1 interface FastEtherner0/0 overload
!
--> access-list 1 permit 192.168.0.0 0.0.0.255
!
--> ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 dhcp

Thank you

[Wizard4777]

if you are still using the starlink wifi router, you can just put default route as "ip route 0.0.0.0 0.0.0.0 192.168.1.1". If starlink router is in bypass mode, your default route should be "ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 dhcp"

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