Minecraft external server does not connect?

I bought Minecraft Win10 Edition a year ago and could not connect to external servers right from the start.

5 servers were already preset for me and I can count on them too.

But if I look for a new server where I want to play he can't connect.

Do you have any idea what the reason could be?

Are those synonymous server for the Bedrock edition?

Thank you Thank you Thank you Thank you Thank you