MTU in PFSense 1436 - how to optimise against rest of network.
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Hi,
Somewhere in my pfsense setup there is an MTU limit of 1436 being set. Not on the interfaces, I have disabled all add-ons running over the top of pfsense, all VPNs down, and downstream the pfsense box runs into an Edgerouter and from that forward to the internet is 1464 and my computer goes into the pfsense box.
My Windows 365 VM (esp Teams) is dropping out on my pfsense box frequently, so much so that I have had to use a bypass (its fine, my DrayTek router runs this in its own VLAN away from all the IOT stuff I have there - with zero problems).
Any ideas where this 1636 MTU size might be hidden, or what is adding to the packet header to bring the MTU size down by 28 Bytes.
What is the optimisation for this and is there any MTU size discovery tool that I can use. I have a number of subnets in use - on the "LAN" (LAN + Subnets) side I read that you can still set this to jumbo frame size no problem, but:MTU Size: 9000 1464 1492 who knows 900Mbps (from component to component below)
Computer ----------> PFSense ----------> Edgerouter -----------> Modem ----------> Optical Termination --------> Web
1436 1436 1464 1492 <--- What the element settings are. I cant change the modem.
But when I am testing non fragmenting packets everything works at 1464 fine until I add pfsense and then I am chopped back to 1436.
How do I fix this?
Thanks
Julian -
How are you testing exactly?
What hardware are you using for pfSense? I assume the interface MTUs are all at least 1500?
Steve
