Pfsense mtu, Do I need to change my MTU? Hey guys

Pfsense mtu, Hi all, I have successfully been running pfSense with VLAN's for a number of years now but I've just come across a question that may have had an effect on the operation/efficiency of the network (without me knowing :O)… I have always had the MTU of each VLAN interface set to 1500, would this mean that any bytes/packets over 1500 would be rejected and if so how is the VLAN tag implemented . Some situations may call for a lower MTU to ensure packets are sized appropriately for an Internet connection. If you don't configure an MTU in pfSense, it will default to 1492 on a PPPoE interface. during the setup of wireguard tunnels on my pfSense, I stumbled over the topic of MSS and how to set it correctly. Do I need to change my MTU? PFSENSE ver 2. I ran across the MTU setting and did a couple google searches and how to test to see what the value should be. Dec 19, 2025 · On This Page Insufficient Hardware Hardware/Driver Tuning Required Duplex Mismatch Traffic Shaping MTU Issues VPN + MTU Issues WAN Connection Client/Testing Method ISP Issues Troubleshooting Low Interface Throughput In situations where the firewall is not transferring as much data as desired. In most cases, the default assumed values for the WAN connection type will work properly. The doc should contain information on common VPN types available in pfSense software: OpenVPN IPsec (routed/policy) WireGuard The following assumes a WAN link MTU of Aug 26, 2025 · MTU (Maximum Transmission Unit): The Maximum Transmission Unit (MTU) size field can typically be left blank, but can be changed when required. 2 CE HW: HP T730 with Broadcom quad port 5709 NIC I've recently started having a bit of instability on my WAN connection (1Gb/s FTTH 1000down/200up) and I'm trying to figure out if its on my router side or if its my ISP. There are many potential causes for this condition, most of which are listed here along with possible Do I need to change my MTU? Hey guys. Nov 4, 2023 · Hello fellow travelers, I’ve been delving into the MSS/MTU issue and made some headway. 1 / FreeBSD 16 — IPv6 Multicast UDP sendto Returns EPERM Oct 26, 2023 · @mauro-tridici said in pfSense as router: question about MTU to be set on a 10Gbps interface (WAN interface to 10Gbps ISP link): what will happen if I will use MTU 1500 on a 10Gbps iface connected to the 10Gbps ISP link? It should work fine. You would think after all these Mar 19, 2019 · When you set MTU it puts a maximum size on the packet and, with TCP, the two ends negotiate the maximum size to use. DHCPv6 Fails on igc Driver Interfaces After Upgrade to pfSense 25. By utilizing the command ping -D -s <packet_size> <destination_ip> in the PFsense router shells on both ends, I successfully determined the correct MTU value for this WireGuard site-to-site connection, which turned out to be 1390. And that is what you should use unless you know for sure that whatever upstream router you're connected to and any switches in between are also using a Setting proper MTU value? Hello everyone, I was browsing through my settings as I do sometimes to try to get familiar with settings and what they do. Aug 26, 2025 · MTU (Maximum Transmission Unit): The Maximum Transmission Unit (MTU) size field can typically be left blank, but can be changed when required. 7. 11. Interfaces with suboptimal MTU values can degrade VPN performance; a document that provides examples/steps to optimize the MTU of different VPN types would help resolve the issue. There are many values and recommendations, but as far as I understand the real question is what is the actual MTU of the WAN link which depends on the type of connection (cable, PPPoE, etc. This means that the maximum MTU of a PPPoE interface is 1492 unless your Ethernet interface and modem support jumbo frames and your ISP supports RFC 4638. ). Nov 16, 2019 · Can anyone explain how to change the MTU/MSSFIX values in pfsense for Openvpn? Please! This have been driving me up the wall. MSS is used by a router to limit the packet size, regardless of what the MTU is set to. Hoping this is an easily answered question.


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