I am subscribed to Internet 150 unlimited.
My hitron modem is in bridged mode
I have a PC running FreeBSD acting as my Internet router / firewall providing DHCP to my LAN clients and doing NAT etc.
Recently I began experiencing intermittent/slow Internet access on all my LAN clients.
I finally isolated the cause as being a bad DHCP option being offered to my router's WAN interface by Shaw's DHCP server.
Specifically the DHCP option is: interface-mtu 576
The option is being offered by DHCP server: 18.104.22.168
This forced my router's WAN interface to change it's MTU from the default 1500 to 576.
This cause very poor Internet performance with lots of fragmentation and dropped packets.
I presume this option must be in error as all Ethernet networks use a MTU of 1500 by default.
I have resolved the issue and restored normal and expected Internet service by superseding this DHCP option on my router by adding this to dhclient.conf
supersede interface-mtu 1500;
My system is Freebsd but I believe this applies to Linux systems as well.
I can only assume that the majority of customers that do not bridge their modems and instead use the hitron for routing are not having connectivity and fragmentation issues? I have no way of knowing if/how the hitron works around the issue.
The purpose of this post is in the hope that you will forward this information to the team responsible for network infrastructure and/or DHCP servers of your Internet service, as they will definitely understand the wide-reaching implications and customer impact of this bad DHCP option.
Thank you in advance for addressing this issue.