Hello and welcome to the community
You may want to check your Win 10 VPN settings - both for sign-in options (if you have username /password set) this will be under Settings>Network & Internet>VPN, as well as the Adapter settings in the network connections section.
Make sure that under the Security Tab that PAP is checked off and no other boxes.
I find that my win 10 changes those on me at will and I always check before connecting
Hope that helps 🙂