First check editions which can be upgraded to from evaluation:
# Dism /Online /Get-TargetEditions
Then launch the activation process with:
# Dism /online /Set-Edition:ServerStandard /AcceptEula /ProductKey:12345-67890-12345-67890-12345
Please remember to replace “Set-Edition” and “Productkey” values with your desired ones.
ifconfig_vtnet0="inet xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx -rxcsum -txcsum -rxcsum6 -txcsum6 -lro -tso"
The above line is taken from /etc/rc.conf. “vtnet0” is the interface description for a virtIO device, on Hyper-V it is named “hn0”.
-rxcsum-/txcsum: disable Rx/Tx Checksum Offloading
-lro: disable TCP Large Receive Offloading
-tso: disable TCP Segmentation Offloading
The parameters above disable hardware offloading to the network card, this may increase CPU usage but some cards are simply not powerful enough to handle high traffic and some hypervisors are not 100% compatible with these settings.
To fix the calendar sync problem on https sites open the config editor and look for network.cookie.same-site.enabled and set this to false. Afterwards restart thunderbird, now the calendar should sync normally.