This is probably related to How would I respectfully disagree with a superior? however the context is a tech forum where the thread starter is asking for someone technically advanced to help, and the culture is more concerned about solving problems than politeness. Is a plain ~違います appropriate in this context?
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Someone well-versed in internet Japanese may need to correct me, but...
You can always soften a straight 違います with saying something like
You can also present a fact, which disproves the claim of your technically advanced helper. There may be no need to say explicitly "you were wrong".
This is not only true for Japanese, but trying to confirm the correctness of the claim in some situation that does not apply to you doesn't give the message "you are wrong", which by itself is not very helpful. You could try
That said, 違います is a lot better than 違う and, although probably unnecessary, may be perfectly acceptable in that particular tech forum, in particular if you are on the end of the technically advanced helper.
If that is the case, there is also the expression