Thanks for the link, James. It's a good, thorough explanation.

I've found that changing the default to 1492 works without any issues, so I'm leaving it at that.

1480 seemed to cause timeouts, but that may have been unrelated - I'm not going to investigate it any further, because life is short after all!

For anyone else who may be interested, the TP Link TL-WDR4300 is a great router in my experience so far.

Upgrading to the latest firmware (3.13.31) gives you a very useful guest wireless network facility and the printer sharing feature, although it requires a client controller utility to be installed on each PC and isn't a proper print server, is actually perfect for SOHO networks because it accommodates cheap host-based laser printers very well, including things like manual duplex printing in the HP driver. The printer client application even works on Win2K, despite claiming XP to be the earliest supported version of Windows. The built-in DNS forwarder is also lightning fast. Haven't tested the media or file sharing features as yet, mind you.

I would definitely recommend the The Asus RT-N66U. This is absolutely top-notch and selling like hot cakes.

Asus RT-N66U

ASUS Amazon

In reply to a post by Kper:

Thanks for the link, James. It's a good, thorough explanation.

np, AAISP is very good at documentation, its just a shame the infrastructure means their prices are too high for most (e.g. I use ~150gb a month, and BT is £26/m but AAISP would be over £60/m !).

For anyone else who may be interested, the TP Link TL-WDR4300 is a great router in my experience so far.

Looks like a very nice set of features router, very similar to the ASUS RT-N66U, and cheaper which is always a bonus

In reply to a post by Kper:

Andrew, do you have any comment on what the correct MTU setting is with this router for an Infinity FTTP connection?

Just wanted to update this thread with the definitive word from BT. The correct MTU setting for 3rd party routers on BT fibre broadband products (FTTP/FTTC) is 1492.

Why am I having problems getting web pages when using a third party router?

If you have fibre/BT Infinity, are having problems getting web pages, and you're using your own router instead of a BT Business Hub, then you'll have to change your router's MTU setting to 1492 and make sure that it's set to PPPoE mode. This way you'll be able to view complex and dynamic web pages normally.

Since some sites like Hotmail / Outlook.com (still) don't do Path MTU Discovery properly (they discard the ICMP packets telling them to reduce the size of the packets they are sending) it can help to set the MTU of all the computers on the LAN behind the router to use an MTU of 1492 rather than the usual ethernet MTU of 1500. I've certainly found that Outlook.com doesn't work properly otherwise.

I've also found that a useful little command line utility for Windows called MTUPath can help to simplify troubleshooting any problem. Hope it may help others too, along with the info above.

One further tip about the TP Link TL-WDR4300 router which may be of use to know is that Skype doesn't always work correctly unless the hardware NAT feature is turned off.

Hardware NAT is supposed to increase LAN-WAN routing speed quite significantly, so it would be interesting to know whether Andrew's 800Mbps figure was with that on or off (or NAT off altogether).

Apparently, OpenWRT doesn't support the hardware NAT feature at all because it would lead to a lot of messy software bodging, so it isn't clear whether the TP Link firmware does in fact include a lot of messy software bodging to accommodate it!

You can tell whether or not hardware NAT is turned on because it introduces an extra non-responsive hop in traceroutes after the router's internal IP address.

In reply to a post by Kper:

Just wanted to update this thread with the definitive word from BT. The correct MTU setting for 3rd party routers on BT fibre broadband products (FTTP/FTTC) is 1492.

BT Business routers default to 1492 automatically - but so many people change it to 1500 and wonder why they have problems.

In reply to a post by Kper:

Just wanted to update this thread with the definitive word from BT. The correct MTU setting for 3rd party routers on BT fibre broadband products (FTTP/FTTC) is 1492.

They say that because 1492 is the maximum MTU that all third-party routers support over a PPPoE connection. I haven't yet found one that supports RFC 4638 out of the box (apart from BT's own HomeHub).

It's possible to patch OpenWRT to support it, and if they ever upgrade their rp-pppoe plugin to 3.11 from 3.8 (released in 2006!) it would "just work" for many routers since a lot already support jumbo frames.

Tomato may eventually get support too.

Since some sites like Hotmail / Outlook.com (still) don't do Path MTU Discovery properly (they discard the ICMP packets telling them to reduce the size of the packets they are sending) it can help to set the MTU of all the computers on the LAN behind the router to use an MTU of 1492 rather than the usual ethernet MTU of 1500. I've certainly found that Outlook.com doesn't work properly otherwise.

Shouldn't your router be doing this for you without you having to mess around with client MTUs? I thought that was the entire purpose of MSS clamping.

For good simultaneous dual band routers i'd say it's hard to beat the Asus RT-N66U. Saw one second-hand on Ebay last week for £44. Seriously considered it as my RT-N16, running Tomato, has been good to me over the years, but in the end i picked up a TP-Link WDR4900.

The WDR4900 is very similar to the WDR4300 but is actually running on an 800MHz PPC chip, rather than the MIPs architecture most routers run on. It's supported by OpenWRT in trunk and has been running fine for me so far (i'm still tweaking settings though, so it's not in production use yet). I'm interested to see how the CoDel stuff in OpenWRT works in comparison to Tomato's QOS.

Left my WDR4900 running an iperf test while i was in the shower this morning.

My very unscientific test results were that it averaged around 394Mb/sec WAN-to-LAN. This is with NAT enabled (but not HW NAT as OpenWRT doesn't support it).

The OpenWRT wiki page for the WDR4300 has someone benchmarking the NAT WAN-to-LAN performance (using http, so not an apples to apples comparison to my iperf test) at 300Mb/sec, so the WDR4900 is a fair bit faster.

Not sure how much of a hit the throughput would take over a PPPoE connection, but since i can't afford a FTTP connection it's a moot point anyway.

Thanks, rhetherington, that's really good info. Well 300-odd Mbps is sufficient to support all but the most unaffordable FTTP, even if PPPoE and HTTP knock it down to less than half that as a worst case.

Is there an easy way to establish a PPPoE connection locally for testing, so that there is no limit from ISP throughput, do you know?...

Using an Android device on the wireless LAN, the speedguide.net analyzer shows an MSS of 1452, so I'm assuming MSS Clamping is working. I wonder whether Timestamping might mess that up by introducing larger headers and reducing the real MSS, but maybe I've misunderstood the effect of that. The PCs have timestamps off, but they seem to be on on Android by default.

It would certainly be a better solution all round to rely on BT's support of baby jumbo frames. Hopefully TP Link will get with the programme and release a firmware update as FTTC and FTTP - and therefore PPPoE - become more and more common. It isn't very sensible for people to be encountering random little problems with using 3rd party routers as a matter of course, and it isn't practical to change LAN MTU settings on a large network, nor to change them for all devices even on a small one. I wonder why they chose to have it default to 1480, not even 1492, though?...

TP-Link have published some WAN-LAN figures, including for PPPoE.

They reckon the TL-WDR4300 can route 935Mbps WAN-LAN over PPPoE!

It doesn't say whether that is using NAT, SPI etc., but if your test is anything to go by, rhetherington, it sounds like they may be special figures from fantasy land!

Interestingly, the Hardware NAT feature seems to alter the ToS and DS IP header fields.