MikeL's ActionTec C 1900 modem HowTo
Last Sunday I made a bad configuration change to my C3000Z, and it
would not connect, even with a factory reset. I called Centurylink,
and they found some other customers name on my account, and said
sorry, call the Solutions Dept. on Monday. Needless to say, I was
furious. Called Solutions Dept. on Monday, got someone with a brain,
and we determined it was probably the modem had croaked - they're
sending me a new one. In the interim, I was able to borrow an older
C1900 (in fact it's my old documented below, borrowed back from a guy
I'd leant it to when his croaked.)
So I'm trying to get the C1900 back to operational, and am documenting
the complete steps, as I'll need to follow them again in the next few
days when the replacement C3000Z arrives.
WAN settings as below 16-Nov.
PP Auto: ena
No PP: dis
Block of static
lan dhcp: Private LAN subnet
pri: 220.127.116.11 (provided)
sec: 18.104.22.168 (provided)
modem ip: 192.168.0.1
begin ip: 192.168.0.128
end ip: 192.168.0.254
lease time: (default)
dns type: default
IP v4 Firewall:
Create rule, do this for each of the following, select TCP & UDP:
drvwymon: drvwymon, 23256
named: zone xfer, 53
cwop: Cumuluscwop, 14580
Then select All Public, and ensure that all the following allow both in and out:
ftp, ftps, http, https, drvwymon, named, cwop
Been running a Zyxel C3000Z dual DSL modem now for several years, too lazy to make a new page for it.
I've had to do some firewall changes. Set to "All Public" and "Low". Add the following:
drvwymon tcp 23256 tcp (my drvwymon program)
RTC-Discord chat 50000-65536 udp (Ellis' online chat app)
Cumulus/CWOP tcp 14580 tcp (Cumulus software)
named zone xfr tcp 53 tcp (named zone transfer)
I have QWest/CenturyLink Dual DSL, using an ActionTec C 1900 modem.
I've had a heck of a time getting it set up for a fairly simple
configuration. I'll jot a few notes here about what I had to settle
The goal was to have DHCP turned on for the inside LAN; any computer
plugged into it, or any computer using wireless would simply be
allocated a protected internal IP address.
The exception is that there are several servers that need to be
available to the outside world.
I have a block of static IP addresses from CenturyLink. When you get
this, you are actually allocated a block of 8 (hence the .248 subnet
mask), however only 5 are available to you for use.
Here's what got it working:
Now the internal computers:
- Browser into modem http://192.168.0.1/
- First time after factory reset or new install, straight to
Advanced Setup->Adminstrative password, configure reasonable
- Advanced Setup->Wan Settings
- ISP Protocol: "auto" (selected is PPPoE)
- PPP username, pswds filled in, "Auto Connect" is checked, "No
credentials" is NOT checked. user/pswd provided by
- IP addressing type: "Block of Static IPs"
- Your gateway address is provided by Centurylink, it's 1 higher
than the last usable IP address in your block. (e.g. I have
.177-.181, gateway is .182.
- subnet mask: 255.255.255.248
- Here's the important one -- DO NOT select "Public Static
Subnet". This would make every internal address available
externally - you only want specific ones available! What this
checkbox does (I talked with a real human at Centurylink that
actually knows what he's talking about!) is basically just tell DHCP
to use INTERNAL ADDRESSES (e.g. 192.168.0.x) for any connections
requesting DHCP. Static addresses (of course within the proper
range) will simply work.
- Static DNS, phone co should have provided this along with your
One last word of caution. The builtin firewall in the modem may get
in the way of your servers activity. If you suspect this is the
problem (data not making it into your server), try moving the server
into a DMZ (advenced setting). If this fixes it, you've got a modem
- On each server (in other words every machine that will be
externally visible), you will hardcode the IP address. Connect
these each to a port on the modem.
- Plug any PRIVATE machines, e.g. in-house wireless, routers or
desktops into other modem ports, but configure them to connect via
DHCP. These will get an internal (192.168.0.*) address and not be
I have a tricky system that uses one of these servers to do SMS
messages with cellphones. This is implemented via HTTP (normal
looking web requests via port 80). The factory default setting of
this modem is for FIREWALL ENABLED, at LOW security. Note that this
setting allows web requests (port 80), outgoing, BUT NOT INCOMING. I
had to go into the firewall configuration screen and select port 80
incoming - this is true for you if you're running a web server.
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