Got NBN now VPN wont work

Hi all,

I am not even a little bit tech savvy but I am hoping someone can help me.
We had the NBN installed this morning and ever since, each time I connect the NBN the internet won't connect to anything.
Is someone able to help me (in plain English) please?
I have a special needs child ans I access a lot of resources for him from overseas.
My VPN provider is Private Internet Access
I am using Windows 10 and Telstra provided modem.
Thank you!
Tink