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Poor network performance


DHCP - Dynamic Host Configuration Protocol
HTTPS - Hyper Text Transfer Protocol Secure sockets
ICMP - Internet Control Message Protocol
ISP - Internet Service Provider
MTU - Maximum Transmission Unit
PMTU - Path MTU Discovery
PPPoE - Point-to-Point Protocol Over Ethernet
RFC - Request for Comments
SSL - Secure Sockets Layer
WAN - Wide Area Network


Poor performance on some internet applications such as:

  • Video streaming
  • Some HTTPS sites do not function correctly.
  • Some SSL communications do not function correctly.
  • General throughput seems lower compared to a previous router.


Go to Network Connections -> WAN Ethernet (WAN PPPoE) -> Settings -> MTU

Change the MTU from Automatic or Automatic (DHCP) to Manual and adjust the value to 1500 for Cable and 1492 for DSL.


We have found that some ISPs are blocking the ICMP notifications that are required for PMTU to work correctly; by RFC1191 section 3.1 definition, PMTU can not send over a MTU of 576 unless the other side it is connected to authorized a larger MTU. Because the ICMP notifications are blocked no authorization takes place and PMTU falls back to 576 per the RFC definition.

A copy of the RFC can be located here: http://www.ietf.org/rfc/rfc1191.txt

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