Calling Mike-W - ubuntu update - how about MTUs? ##EUREKA###

[RogerS]

Woo hoo. Did a search on Alice plus a few others and came across this site. You should see the grief that people are getting using Alice's CoS. OK - I know these posts originate in Germany but.....
http://www.toytowngermany.com/search/?q=alice

I've not had time to read through them all but Andy, it would seem you are not alone. Almost makes me pine for BT or Sky :wink:

 

[dedee]

I am not alone and what's more I've found a solution - kind off, see later - that has been used by other users over here

http://www.completefrance.com/cs/forums ... wPost.aspx

The first page on Page 5 includes a reply from the nationwide that suggests adjusting the MTU rate on the router.
The OP on page 7 managed to change her MTU to 1200 and hey presto it worked.
Do you guts understand MTUs.

Problem is I cannot find anywhere on the router to do this - ideas anyone?
I am awaiting a response from the OP

We will phone Alice later and see what they say.

Fingers crossed

Andy

 

[dedee]

Cracked it!!

In Network Prefs>Advanced> Ethernet> set MTU to custom and changed value to 1200.

AND IT WORKS Alle bloody lujah.

I cannot thank enough all the contributors to this thread. So many people have worked so hard to try and solve this and all the time it was a setting on the Mac. I am not at all sure when how either this got changed or Alice changed its ability to read MTU at a rate of 1500. caveat I do not know of what I speak.

Cheers

Andy

 

[TrimTheKing]

MTU is Maximum Transmission Unit and this is the maximum packet size that the router (or ethernet) will transmit. Lowering it is usually done when you are using a VPN of some kind because at maximum packet size you can have issues when the VPN headers are added and make the payload higher than the max allowed packet size (1500 for ethernet). If the packet is too big then the router will 'fragment' them, which can cause issues.

I have experienced this at work before with BT who have smaller MTU's set on some of their offerings but not all...

This all makes sense now. The MTU on your Mac is 1500, as will be the MTU on the Alice router. Problem is, when you are sending packets at 1500 on port 80 (http) they are at the full 1500b, but when you get to the SSL part there is an additional VPN/SSL wrapper put around the packets taking them over the MTU and thus begin fragmenting. Fragmenting is another area where there is 'wiggle room' in the RFC so two differing technologies (your router and whatever endpoint Nationwide use) obviously are not compatible.

Great news that it's fixed though, well done

 

[kityuser]

Cracked it!!

In Network Prefs>Advanced> Ethernet> set MTU to custom and changed value to 1200.

AND IT WORKS Alle bloody lujah.

I cannot thank enough all the contributors to this thread. So many people have worked so hard to try and solve this and all the time it was a setting on the Mac. I am not at all sure when how either this got changed or Alice changed its ability to read MTU at a rate of 1500. caveat I do not know of what I speak.

Cheers

Andy

MTU, well bugger me if I wasn't going to suggest that. wrong value causes encrypted packets to be "broken up" and thus corrupted, or at least perceived that way.

as stated, VERY common on VPN problems

blow blow blow, should have suggested it, still sorted now 8)


this is why I like playing with wood and guitars :wink:


Steve

 

[RogerS]

Brilliant, Andy. Great news! ccasion5:

Could have sworn I suggested that in my first post but it seems to have been deleted :^o

 

[dedee]

It's all immaterial now but what do you think happened?

1) An upgrade to the mac changed the network settings & increased the MTU

2) Nationwide changed their bit so a large MTU rate could no longer cope

3) Alice (the ISP) changed it's bit so a large MTU rate could no longer cope

It wasn't user instigated that's for sure.

Andy

 

[TrimTheKing]

It's all immaterial now but what do you think happened?

1) An upgrade to the mac changed the network settings & increased the MTU

2) Nationwide changed their bit so a large MTU rate could no longer cope

3) Alice (the ISP) changed it's bit so a large MTU rate could no longer cope

It wasn't user instigated that's for sure.

Andy

one of or combination of 1/3. Number 2 isn't an option, it is what it is, nothing to do with NW.

 

[RogerS]

It's 3. The Mac MTU has remained constant at 1500 for a long time.