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2830N Plus On TalkTalk FTTC - Weird MTU?

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26 Nov 2011 21:34 #70228 by dave_leeds
2830N Plus On TalkTalk FTTC - Weird MTU? was created by dave_leeds
Hi Folks,

Just got a 2830n Plus for TalkTalk's FTTC service - replaced their supplied flimsy Huawei affair as it's fairly useless

Got internet access working fine with the Openreach FTTC modem plugged into WAN2 - disabled WAN1 (ADSL) on the Draytek, and set WAN2 (Ethernet) to dynamic/static IP, this gets a WAN IP from the Openreach modem as expected.

I'm having fun and games with slow torrent speeds, as well as weird drop outs on iPlayer, ITV Player, and certain web sites - ping stays constant so the connection isnt going down. Putting the talk talk router back on resolves these issues, and torrent speeds are back up to a breezy 4mb/s :)

I'm fairly confident it's an MTU issue, as running ping tests to check my max mtu it seems to be all the way down at 1300 - extremely low in my experience

The draytek was set to 1442 so it wasnt that causing the bottleneck - is it possible the Openreach modem is set at 1300?

Has anyone else got an openreach FTTC modem working alongside the 2830xx? Have i missed any config steps to get it working right? I've noticed the 2750xx needs VLan config, but is that just because it uses it's own fibre modem??

Any input would be appreciated,

Thanks

Dave



results of ping test:

lowest unfragmented packet size on ping test comes back as 1272 - see below

C:\Users\Dave>ping -l 1272 -f www.google.com

Pinging www.l.google.com [173.194.67.147] with 1272 bytes of data:
Reply from 173.194.67.147: bytes=64 (sent 1272) time=27ms TTL=46
Reply from 173.194.67.147: bytes=64 (sent 1272) time=26ms TTL=46
Reply from 173.194.67.147: bytes=64 (sent 1272) time=26ms TTL=46

Ping statistics for 173.194.67.147:
Packets: Sent = 3, Received = 3, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 26ms, Maximum = 27ms, Average = 26ms
Control-C
^C
C:\Users\Dave>ping -l 1273 -f www.google.com

Pinging www.l.google.com [209.85.147.104] with 1273 bytes of data:
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 209.85.147.104:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

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29 Nov 2011 10:36 #70252 by boe323
open telnet, point it to ip address, type in wan mtu ?, to find out what it is, then type wan mtu and what ever you want to set it to, i find that 1478 is fantastic, but im on bt.Then you will probabley want to set mru to the same, wan ppp_mru 1 and what ever you set it to, ie, wan ppp_mru 1 1478. Sometimes you need to use wan ppp_mss instead, if you open telnet and connect to your router and type ? you will list your commands.Basiclly you need to change yor mtu using telnet.

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