Hello - I have done my best to read thru as much as possible, but I can not find an answer. I have a client that I recently sold a routerboard 532A.

The unit connects to a PPPoE DSL account, and does NAT and a little bit of port forwarding (nothing MT can't handle! ) The customer can not get to every web site including sites they consider important. I plug the old DLink DI-604 back in, and they can get to the sites. The D-Link was configured for an MTU of 1492 or 1496 (I can't remember). I've tried the following on the MT box: 1454/1480/1492/1496 - the Ethernet interface is set to 1500 and is connected directly to the ethernet port of the DSL modem.

Does any one have any suggestions? A very perplexing problem. Thanks for any suggestions you can offer. (again, some sites like google.com work, some like msn.com do not)

did you change the mtu from the ethernet port or from the pppoe client interface ?
did you try a transparent proxy as workaround ?

Do you think changing the Ethernet MTU will make a difference? Seems to me a transparent web proxy is not the best way of handling things - even as a work around. THe way the customer sees it, the cheap-o $45 Dlink DI-604 is doing a better job!

I will give the MTU on the physical interface a change - I'm working remote so I'm worried about the impact it will have.

If anyone else has a suggestion - I would like to hear about it as I have no physical access the router (worried about taking them completely off-line until tommorow!)

Are you check TTL ?

/ ip firewall mangle
add chain=prerouting in-interface=WAN action=change-ttl new-ttl=set:65 comment="TTL FIX" disabled=no
add chain=forward protocol=tcp tcp-flags=syn action=change-mss new-mss=1440 comment="MSS FIX" disabled=no

Incredible - that seemed to have fixed the problem first try. Very good, thank you for that information. I'm not exactly sure what it is doing. Might you be able to describe how that affects the packets and why it works?

Thanks again Very happy!

2)it changes packet mass and 1)sets time to live to 65 so packets last longer