Let's learn from the configuration of the popular public cloud provider:

vultr private network configuration:

Vultr recommends that the MTU of the private network is set to 1450

# Private network: net5d808a0cc22dbDEVICE=eth1ONBOOT=yesBOOTPROTO=staticIPADDR=10.25.96.3NETMASK=255.255.240.0MTU = 1450 

Let's take a look at digitalocean:

# Created by cloud-init on instance boot automatically, do not edit.#BOOTPROTO=noneDEVICE=eth1HWADDR=ba:11:3e:a9:43:5bIPADDR=10.138.132.226MTU = 1500NETMASK=255.255.0.0ONBOOT=yesTYPE=EthernetUSERCTL = no