DM200 modem - - I cannot access my company's network folders

[antinode]

> DM200 modem - - I cannot access my company's network folders

   "access" how, exactly?

   "cannot" is not a useful problem description.  It does not say what
you did.  It does not say what happened when you did it.  As usual,
showing actual actions (commands) with their actual results (error
messages, LED indicators, ...) can be more helpful than vague
descriptions or interpretations.

   If the only problem which you have with Internet access is a problem
with file sharing for some particular file server, then, based on
approximately no useful information, I'd guess that the problem lies
with the file server or the client configuration, and not with the
"modem[+router]".

[Mark5522]

Hello,

Sorry that I could not provide a better description; when used the Netgear community system, it would not allow me to provide any detailed information, only the general description (the box for detail seemed  to be blocked; I could not type anything in that box).  So I had to just initiate the request with very little info, and plan to provide the details later in an email.

Anyway, here are more details:

I am having trouble working from home, because I cannot access files or folders on my company network.  I have CenturyLink DSL, a NetGear DM200 modem, and a LinkSys WHW03 wireless router.

With this system, I can access my work Outlook email, participate in Teams meetings, access the internet, and do basic things like that.  But I have no access to folders or files on my company network; this access seems to be blocked, and when I try, I get error messages that the files are unavailable. This occurs even if I am directly connected via an ethernet cable between my laptop and the NetGear modem.

However, my company's VPN (GlobalProtect Version 4.1.1-14, from Palo Alto Networks, Inc.) says it is connected.  I have recently re-installed this VPN, with the help of my IT department.

I also recently updated the firmware on the NetGear modem.

Another important note:  This access problem only occurs on my home network.  If I use other remote WiFi (coffee shop, airport, etc.), everything works fine; I can access my work folders and files easily.

So the only common factors are; the NetGear modem, and my ISP.  I have worked with my ISP for hours and hours and hours (communicating with 10-15 different technicians), and they have come to my house and checked the hardware.  My ISP can find nothing on their end which is causing this problem.

So, I need to now find out if there could be something in my NetGear modem which is causing a problem.

Can you please help?

Thanks,
Mark

[michaelkenward]

---

@Mark5522 wrote:

So the only common factors are; the NetGear modem, and my ISP. 

Did your tech team try using a different modem to rule that out?

Just one thought, if you have been playing around with the modem, updating firmware, resetting it and so on, then it may have its router mode turned on.

By default, the DM200 has some limited router capability. You need to turn that off if you have a decent router on the network.

The Quick Start guide for the DM200 explains how to go ab out this.

If you visit the support pages:

Support | NETGEAR

you can feed in your model number and find the documentation for your hardware.

@Mark5522 wrote:

With this system, I can access my work Outlook email, participate in Teams meetings, access the internet, and do basic things like that.  But I have no access to folders or files on my company network; this access seems to be blocked, and when I try, I get error messages that the files are unavailable. This occurs even if I am directly connected via an ethernet cable between my laptop and the NetGear modem.

Your DM200 is probably the dumbest bit of kit on your network. Unless you have that router bit turned on, the modem does very little in network terms beyond connecting your router, and everything attached to it, to the Internet.

What happens then is down to what happens at the bits where the hardware really does have some control over matters.

[antinode]

> [...] I have CenturyLink DSL, [...]

   Does your DSL service use PPPoA or PPPoE?

> [...] a NetGear DM200 modem, and a LinkSys WHW03 wireless router.
> [...]

   By default, the DM200 is a modem+router, not a simple modem.  This
can cause a variety of problems if you connect a (that is, another)
router to it.

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual.  Read.  Look for "Disable the
Modem's Routing Features and Use the Modem as a DSL Modem Only".

> [...] my company's VPN [...]

   Another potential trouble source when multiple routers are cascaded.

[Mark5522]

Thanks - - this is good feedback.

Yes, my modem is set to the modem/router mode.  I do have the manual for the DM200, and I did try resetting it to "modem only" mode, but then my whole system was down because my wireless router would no longer work with the modem's signal.  I couldn't figure out how to get this fixed, and so I did a factory reset on the modem, to get going again.
Do you have any ideas about what would have changed in the output from the modem (when in "modem only" mode), such that the router would have stopped working?

Thanks,
Mark

[Mark5522]

To answer your question "Does your DSL service use PPPoA or PPPoE?", I do not know.  I do not know what these terms mean.  Could this be a factor in my problem?  I could probably find out which they use.

[michaelkenward]

---

@Mark5522 wrote:

I couldn't figure out how to get this fixed, and so I did a factory reset on the modem, to get going again.

This means that it is now back in modem/router mode.

If that is the cause of your problems, which seems likely, then you need to work out how to get it to work in modem only mode.

I assume that you know the settings you need to feed into the modem to get it to connect.

We don't know what you did and why it broke the internet connection, but my inclination would be to get the DM200 to work in modem only mode. Check that it work by going on line without getting the router involved. Just plug a PC into the modem.

When you  know it works, reset the router and set that up from scratch.

Here too, the manual for your router should help.

The router has to negotiate a connection through the modem. So you have to feed in details there too.

When you throw a VPN into the picture, you are entering strange territory. Your IT team should be able to help you navigate this maze.

Sadly, even when you get things working at your end, your corporate network may present a brick wall. But at least you will have removed a couple of layers.

[Mark5522]

For a little history - - I have never been able to get to my company network through my home setup. Nothing new; I'm just trying to get it functioning because I now need to work from home because of covid 19.

Anyway, I'll try the "modem only" mode - - But a quick question - - when I am switching to "Modem Only" mode, should I click the "Passthrough VLAN" box, or not?  This option pops up when I click on "Modem Only" mode, but the DM200 manual doesn't say anything about this.

[antinode]

> To answer your question "Does your DSL service use PPPoA or PPPoE?", I
> do not know. [...]

   Look at the DSL configuration information on the DM200 when it's
working (in modem+router mode).  In the DM200 User Manual, look for
"Manage the Internet Settings Manually".  BASIC > Internet.  All that
stuff (which, I presume, was configured automatically by the "Internet
Setup Wizard") would be interesting.  According to the DM200 Manual, the
PPPoA/PPPoE (encapsulation) option seems to be (mis-)labeled "Internet
Service Provider".

   If your CenturyLink service uses PPPoA, then I believe that you can
_not_ use the modem-only mode on the DM200.  If your service uses PPPoE,
then modem-only mode should work, but you'd need to configure the PPPoE
mode and credentials on your _router_ (about which I know nothing).

> [...] I do not know what these terms mean.

   The details are (far) more than you need to know, but:

      https://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_ATM
      https://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernet

   The critical thing is that your ISP almost certainly uses one or the
other, and your modem needs to agree.  With PPPoE, the required
negotiation and authentication can (at least in principle) be done by a
separate device (like your Linksys router).  With PPPoA, I believe that
you're stuck with the DM200 as a modem+router.

   If your service uses PPPoA, and the DM200 must stay in modem+router
mode, then you might want to configure your Linksys router as a wireless
access point, rather than as a full-function router.  That's the other
way to avoid multiple-router problems.

   Or see if you can persuade CenturyLink to switch your service
(encapsulation) from PPPoA to PPPoE.

> [...] when I am switching to "Modem Only" mode, should I click the
> "Passthrough VLAN" box, or not? [...]

   I don't know.  In my experience (which is PPPoA, by the way),
CenturyLink does not use VLANs, so my guess is that such a setting
wouldn't matter.  But, if there are only two choices, then a little
experimentation might be faster and easier than research.

> We don't know what you did and why it broke the internet connection,
> [...]

   "We" may not all be equally ignorant on this topic.

   If you take a modem+router which had been negotiating a PPP link, and
you make it stupid (modem-only mode), and you change nothing else, then
I believe that I can explain what went wrong.