https://www.ef.com/ca/english-resources/english-grammar/conditional/ If the link didn't work, then you would try this other one. (type 2 conditional) If the link doesn’t work, then you will try this other one. (type 1 conditional)

Thanks, But when should we use conditional cases?

You would say: If the link doesn’t work, use this one. If the link doesn’t work, you should use this one instead. If the link doesn’t work, you can try this one. If you say “you must” or “you have to” this would be saying that they are obligated to use the other one. The best way to make a suggestion is to use the sentences I wrote above. Also are you talking about the future or past? It’s better to use “doesn’t”. If (in the future when you try) the link doesn’t work.... instead of if the link didn’t work (the person already tried it in the past). Hope this helps