Hi
I am using a WiFi network which is a 5G Android phone with connection sharing (WiFi access point) to connect the built in WiFi on a Pi 4.
I am sending large packets because I'm tunnelling raw ethernet frames using VXLAN over Wireguard and sometimes I'm getting some instability.
The MTU of the phone wifi network is 1472 (if I ping I can send a payload of 1444, so with 28 bytes of header that makes the MTU 1472), but when I query the MTU of the link using IP link it says 1500.
When I use NMCLI to query the settings it says "auto".
So I think that I am running into MTU issues because the kernel thinks that it can send 1500 byte packets but actually over 1472 won't get through.
Is automatic MTU supposed to work?
It's a bit of a pain to set manually because it's per "connection" rather than per interface.
thanks, DNJ
I am using a WiFi network which is a 5G Android phone with connection sharing (WiFi access point) to connect the built in WiFi on a Pi 4.
I am sending large packets because I'm tunnelling raw ethernet frames using VXLAN over Wireguard and sometimes I'm getting some instability.
The MTU of the phone wifi network is 1472 (if I ping I can send a payload of 1444, so with 28 bytes of header that makes the MTU 1472), but when I query the MTU of the link using IP link it says 1500.
When I use NMCLI to query the settings it says "auto".
So I think that I am running into MTU issues because the kernel thinks that it can send 1500 byte packets but actually over 1472 won't get through.
Is automatic MTU supposed to work?
It's a bit of a pain to set manually because it's per "connection" rather than per interface.
thanks, DNJ
Statistics: Posted by dieselnutjob — Mon Jun 23, 2025 9:27 pm