Open an Elevated Command Prompt and run this command to view current MTU size of the available IPv4 sub-interfaces (Can also be done with IPv6):
To change the MTU size of sub-interface no. 1 (See "Idx" from above command):
netsh interface ipv4 show interfaces
Related Registry settings to Configure MTU size.
netsh interface ipv4 set subinterface 1 mtu=1500 store=persistent