SR MBP and Netgear WGR614 : connection OK, not all web sites reply

[boz0]

Greetings,

I am the (almost) happy owner of a brand new SR MBP. I had no trouble at all associating it with my Netgear WGR614. I am using this AP only as a wireless switch, the DSL connection being actually driven by a linux box.

LAN connections work smoothly between the MBP and the linux box : large file transfers, no hiccups on my SSH sessions, and so on.

Internet connections, though, do have a problem : most web sites don't display, with only a few of them working (Google, for instance). The ones that don't work begin to load (the status bar indicates several requests, including pictures), but freeze along the way, never displaying anything, whether using Safari or Firefox.

- Those same problematic sites display just fine on my windows box and the linux box both, so it's not a remote site problem
- Those same sites don't work either when plugging the MBP on the Netgear, and wireless LAN is OK, so it's not a purely wifi-related problem

I'm suspecting some kind of incompatibility between my Netgear and the MBP. I've tried lowering the MTU on the MBP, but it hasn't changed a thing.

So, to sum it up : using the Netgear for any kind of LAN activity is fine, but when it comes to internet access, things are screwed up.

Any advice would be greatly appreciated!

 

[boz0]

UPDATE : I tried bypassing the Netgear by using a plain old switch, and the problem persists. It's probably some kind of IP problem between my MBP and the Linux gateway (Ubuntu box running a 2.6.15-28 kernel and offering NAT via Netfilter).

 

[mkrishnan]

How is the Windows box connected to the network? Does it go through the Linux gateway box too?

 

[boz0]

How is the Windows box connected to the network? Does it go through the Linux gateway box too?

Yes, everything goes through the linux box (the USB DSL modem is physically plugged on the linux box). The Windows box is on a wifi LAN.

As for the MBP, I've tried using wifi, plugging it physically on one of the ethernet ports of the AP, and using another spare switch to link it to the linux box, the results are always the same.

 

[mkrishnan]

You said the Windows PC is on a "WiFi LAN".... do you mean it's on the Netgear, or is it connected in another way? Can you layout your entire network from the modem down, please?

 

[boz0]

Oh, and by the way, running Windows on the MBP gets exactly the same results!! Some sites work, but most just won't!!

A chipset problem?

 

[boz0]

You said the Windows PC is on a "WiFi LAN".... do you mean it's on the Netgear, or is it connected in another way? Can you layout your entire network from the modem down, please?

The modem is plugged on, and driven by the linux box (NOT on the Netgear). So the WAN port is on the linux box.

The linux box is physically linked to the netgear (that model offers 4 ethernet ports). All other machines (the windows PC and the MBP) are wirelessly linked to the netgear. In other words, I'm only using the netgear to switch packets, not as a router.

 

[zioxide]

It's not your MBP. It's either a problem with the linux box or with your isp.

Try plugging straight into the DSL modem, bypassing the wireless ap and the linux box and see if it still isn't working.

 

[mkrishnan]

The modem is plugged on, and driven by the linux box (NOT on the Netgear). So the WAN port is on the linux box.

The linux box is physically linked to the netgear (that model offers 4 ethernet ports). All other machines (the windows PC and the MBP) are wirelessly linked to the netgear. In other words, I'm only using the netgear to switch packets, not as a router.

So are you set up something like this:

Modem -> Linux box (USB or ethernet)
Linux box -> Netgear WAN port (ethernet)
Netgear -> Windows PC, Mac (wifi)

You do have the linux box on the wan port of the netgear, right? Does it make any difference whether the Windows PC is off or on when you try the Mac?

I dunno... I suspect you may need to go into the NAT logs on the Linux box. You might try for more specialized help at the Ubuntu forums. I don't know how many people here know how to configure an Ubuntu box acting as a NAT... and that's almost certainly where the issue lies.

 

[boz0]

You do have the linux box on the wan port of the netgear, right? Does it make any difference whether the Windows PC is off or on when you try the Mac?

Nope, on one of the LAN ports. As I said, I don't route packets through the netgear, I only switch them (from the wireless side to the wired ports).

I dunno... I suspect you may need to go into the NAT logs on the Linux box. You might try for more specialized help at the Ubuntu forums. I don't know how many people here know how to configure an Ubuntu box acting as a NAT... and that's almost certainly where the issue lies.

The weird thing is, it's not completely blocked. I'm under the impression that it gets stuck when it starts requesting images.

At any rate, thanks for your help.

 

[boz0]

It's not your MBP. It's either a problem with the linux box or with your isp.

Try plugging straight into the DSL modem, bypassing the wireless ap and the linux box and see if it still isn't working.

It's a USB modem, and I'm not sure MacOS supports that

Beyond that, my DSL connections works just fine for the rest of my LAN.

 

[boz0]

Does it make any difference whether the Windows PC is off or on when you try the Mac?

Nope, no difference at all.

I've set up Squid on the Linux gateway. This workaround works just fine, though, I'd much rather solve the actual routing problem.

 

[boz0]

Oops, I forgot to post the solution to this problem. I just lowered a bit the MTU on my MBP (from 1500 to 1492) so that it would be consistent with the MTU on my router's WAN interface.