One thing I noticed recently was that my firewall, running Linux, was getting a MTU of 576 bytes, instead of the normal 1500 bytes. This was being set by the Rogers DHCP server (option 26). 576 was common back in the days of non-error correcting modems, but hasn't been needed since then. If you're running dhcpcd, you can edit /etc/sysconfig/network/dhcp and change the line 'DHCPCD_USER_OPTIONS=""' to 'DHCPCD_USER_OPTIONS="-M"'. This will disable the DHCP MTU setting and use the configured MTU. Using a 1500 MTU will improve network efficiency, as 576 bytes will cause 3 packets to be sent, instead of 1, each with an IP header and also causes a lot more work for all the routers along the path. You can verify the MTU with a ping -s 1500 <destination>. If that works, then you have a 1500 byte MTU along the entire path to the destination. I found this because I was curious as to why the Ethernet port connected to the cable modem was not getting an IPv6 link local address. IPv6 requires a minimum MTU of 1280 bytes so, with 576, IPv6 wasn't allowed. I have advised Rogers of this and the person I was speaking to agreed it should be 1500. Let's see if they fix it.