D-Link DSL-300G+ & Belkin Router problems

Can anyone shed any light on my problem? I have a LAN based on a Belkin 4
port cable/DSL router gateway and connect a D-Link DSL-300G+ ADSL modem to
the WAN port.
Initially everything worked as expected, I could access the broadband
connectin from any computer on the LAN.
But now something has changed, so that I can only connect to the net if I
plug the modem directly into an individual computer and every time I use a
different computer I have to delete the address information and recreate it
on the new computer.

When I contact my work tech support to re eastablish the VPN connection,
they tell me that the modem is acting as a DHCP server and that only the
router should behave in this manner.

Anyone know how to disable the DHCP function on the DSL-300G+?

Any help would be greatly appreciated.

Des

"Des Small" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Can anyone shed any light on my problem? I have a LAN based on a Belkin 4
> port cable/DSL router gateway and connect a D-Link DSL-300G+ ADSL modem to
> the WAN port.
> Initially everything worked as expected, I could access the broadband
> connectin from any computer on the LAN.
> But now something has changed, so that I can only connect to the net if I
> plug the modem directly into an individual computer and every time I use a
> different computer I have to delete the address information and recreate
it
> on the new computer.
>
> When I contact my work tech support to re eastablish the VPN connection,
> they tell me that the modem is acting as a DHCP server and that only the
> router should behave in this manner.
>
> Anyone know how to disable the DHCP function on the DSL-300G+?
>
> Any help would be greatly appreciated.
>
> Des
>
>

Des,
I had much the same happen but with the D-Link modem and a Buffalo G54
Airstation. You need DHCP servers on both the modem and the router.

I assume you are using adsl, in which case the normal operation would be as
follows:
The modem is set to PPPoA and runs a DHCP server. The router runs a DHCP
client on it's WAN port. On initial connection, the modem serves an address
in the private address space 192.168.0.0/16, usually 192.168.0.2, to the
router. Meanwhile, on the LAN side the router runs its own DHCP server
which must be *in a different sub-net* to the modem. Your PC clients will
then get their IP addresses and routing information from the router DHCP
server. As far as I know you can't change the subnet that the 300G+ modem
uses, so you must make sure that the Belkin router's DHCP isn't in set to
that subnet. I have no idea if the Belkin router can be changed or not but
think it is highly likely. So that's the first issue.

Now the second issue, and this is where things try to get clever. Once the
initial connection has been made between the modem and the router *and* the
modem has established the adsl connection, at the next DHCP renewal the
modem doesn't renew the private address previously given but substitutes the
public address which it has been given, in turn, by your ISP. To ensure
this happens promptly the initial (private IP) lease period is only 30
seconds. The modem passes on the public address with a longer lease but
this is only 60 seconds, which in DHCP terms is still a very short lease.

So the second problem is that not all routers can handle these short lease
periods It all depends on how the firmware, which manages the lease
renewal, has been written. I don't know if the Belkin is compatible or not,
however, the Buffalo Airstation firmware was modified to be compatible with
the 300G+ and I was not expecting any problems. Initially my installation
worked fine but then, after about one week stable operation, it lost the
connection between the router and the modem. Re-starting both modem and
router got things going again for a short time and then it would fail again.

I traced the problem to the DHCP server in the modem which had defaulted to
the 30 second address lease period rather than 60 seconds when serving the
public address. The router DHCP client just couldn't keep up with the
renewal requests, which it was trying to do every 20 seconds, in order to
ensure that it had a continuous lease. (Hope this all makes sense!)

I've searched for 300G set up information, but you need to use the telnet or
local console ports to do any of the clever stuff and I'm dammed if I can
find any information on the commands available, either syntax or meaning!
Perhaps someone on here can help with this?

After much messing around I inadvertently solved my problem when I tried
re-setting both modem and router to factory defaults, by pressing their
respective re-set tits. On doing this the modem died and has refused to
come back to life since. So if yours is a similar problem I'm afraid I can
help no further 'cos at that point I cut my losses and got an adslNation
X-modem instead!

Hope this is of some help and at least gives you some clues as to where to
start looking.

Good luck
SNG