Got it, I didn't think about cleaning cache, I thougt it was an universal problem as some days ago forum was down. Thank you all.
Next time if a particular url is inaccessible to you, try using it in the
https://www.downforeveryoneorjustme.com website. If it is not a local issue to you, it should load up fine with this site and it'd let you know. If the URL is inaccessible universally, it would tell you that too.
That was a SMF error so probably it would anyway say online even if it isn't.