Is there any way to stop this from happening without making the Chrome Browser my default?
I don't even like samsung browser but Chrome doesn't work correctly when signing up to public WIFIs, I can't believe Google has still not sorted this problem.
I have no issues signing into public wifi with mine... I think the bug for that is on Samsung's side, not Chrome.
To stop the browser from opening URLs you need to go to the App settings for Samsung Browser and clear defaults there. That way it'll ask you which browser to use the next time a supported link is opened.