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MTU setting not working as expected

pr flag
cjc

Ubuntu 20 /etc/network/interfaces is set and server boots. While we can connect in, getting out is not possible. When the MTU is updated to 1500 vs 9000, everything works as expected.

We checked another server that is working. For some reason, there are duplicate routes. One is set for onlink and the other for static. The server that has issues only shows onlink; however, static is set in interfaces.

We thought that is might be MTU PATH DISCOVERY overriding the MTU; however, I do not see where that could be set. We already looked in /proc.

While we have not checked the switch, we are running out of ideas.

Thoughts/comments/suggestions are appreciated.

Thanks Chris

guiverc avatar
cn flag
Ubuntu 20? No such product, so do you mean Ubuntu Core 20 Server? (the *year* format signifies different products to the far more widely used *year.month* products; ie. specialist server products for use in devices, appliances or the cloud).
chili555 avatar
cn flag
/etc/network/interfaces is deprecated in Ubuntu 20.xx in favor of netplan. Welcome to Ask Ubuntu.
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