Update your DNS lookup to use google public DNS instead of your ISP. This can resolve invalid url issues with VPN and speed up performance. Below content is copied from:
The Google Public DNS IP addresses (IPv4) are as follows:
The Google Public DNS IPv6 addresses are as follows:
You can use either address as your primary or secondary DNS server.Important: For the most reliable DNS service, configure at least two DNS addresses. Do not specify the same address as both primary and secondary.
You can configure Google Public DNS addresses for either IPv4 or IPv6 connections, or both. For IPv6-only networks with a NAT64 gateway using the
64:ff9b::/96 prefix, you can use Google Public DNS64 instead of Google Public DNS IPv6 addresses, providing connectivity to IPv4-only services without any other configuration.
Some devices use separate fields for all eight parts of IPv6 addresses and cannot accept the
:: IPv6 abbreviation syntax. For such fields enter:
0 entries to
0000 if four hex digits are required.