I'll pop in here, as one of the people who rejected. But, before I explain things out, I'll just leave this here link to a fairly good explanation why I chose to reject. It's already been mentioned in the comments, but I want to relink it, because it's really the core of why I rejected the edit.
In short, your edit wasn't a matter of style, or fixing typos; you were fundamentally changing the content of the answer. And that's generally not cool. If you think an answer is wrong, you can downvote it, you can comment on it to let the answerer know, or you can post your own answer, none of which were things you had tried prior to suggesting the edit.
Now, that's not to say that I'll always reject edits made primarily for correctness; if this were a long-accepted post, with dozens of upvotes, with both the question asker and answerer not having been on the site in months, meaning the answer is likely to stay on top no matter what, and you had already tried commenting about the issue, and other people had all agreed, and you had mentioned in the edit description something along the lines of "Fixing port number as per agreement in the comments", I probably would have double-checked the comments, and whacked the accept button. For a brand-new answer on a brand-new question, where the answerer had themselves admitted they had no way to know if it was correct? Downvote, comment, and/or leave your own answer. Especially since, as the asker, you can un-accept the given answer pretty much any time, if you feel it's incorrect.
(At least, that's my thoughts on the matter.)