Sync problems with DSL and a Fritz router

[Lord_umbs]

please helppppppppp

hello to all, I have a win xp pc connected to a DLS modem and I'm 24h a day in internet.
I've bought first a netgear dsl modem router and then changed with a Fritz wlan dsl router mod 3070 because of the following:
the problem that I have is:
I've already configured to connect the router in internet.
the dls cable is connected
the lan cables of my 2 pc are not connected
the router syncs to dsl and is connected.
as soon as i connect one or both dsl cables into the router the dsl led starts flashing and there is no connection (sync) to dls.
when I remove the cables it works again.
I've already changed all the cables and the network 10/100 cards.
when both cables are connaected the home network is working properly, i can transfer files within the 2 pc and from both configure the router but no0 sync to DSL.
please help before I apply a 380 Volt cable to both pc and Router and destroy them forever and buy a note block.
thanks in advance
Umberto

[Byte 2.0]

Very odd issue.

Seems like i remember a virus that caused issues and would use so much bandwitdh it would knock DSL out of sync but that was along time ago.

So I take that to be clear, when you have the DSL modem connected, the DSL modem displays it is in sync.

You can then connect the router to the DSl modem and it keeps sync.

then you connect the PC's to the router and the DSL modem always loses sync?

First I would start with a good up to day virus scan and try again.

If issue remains,

For a test try to connect each PC one by one to the DSL modem and see if the issue remains.

[Lord_umbs]

thanks for your suggest but:
both computers are able to activate the modem.
the router is also a modem and when I connect both computers to the router
there is no sync with dsl.
I've just installed brand new win xp and no virus found.
helllllllllllllllllllpppppppppppppppppp

[glc]

Confirm that you are connecting an unfiltered phone line into the DSL jack on the modem/router, and you are connecting the computers into switch ports on the router with Ethernet cables?

[Lord_umbs]

ok to be clear, from the telephone plug on the wall to the dsl splitter, from the DSL splitter to the DSL modem-router.
the 2 pc are vial 10/100 lan cables in the modem-router connected and the modem-router can't sync.
if i disconnect the two LAN cables, the sync is ok.
u

[kodmaster]

have you contacted your isp to ssee if it's a problem on their end also try contacting netgear tech support and see if you can get a replacement for a defective unit

[glc]

kod, please read more carefully - the Netgear is long gone.

I think the Fritz router is defective or you have a problem with your DSL line. Did the Netgear do the same thing? Confirm the modem is plugged into the UNFILTERED side of the splitter - what happens if you plug the router directly into the wall jack with no splitter?

[Lord_umbs]

ok, I've changed the fritz box with a us robotics wlan-lan router (not modem).
us robotics is connected to my t430 modem.
when I connect per lan the 2 pc then the dsl led on the modem blinks.
if I disconnect the cables and connect one of the 2 pc with wlan usb adapter everything is ok.
I think that it is something connected to autonegotiation?

[glc]

Try changing the settings on the wired network adapters to 10 megabit half duplex. I've never heard of anything like this causing the DSL to lose sync - especially now that you have a separate modem and router.