One certain website won't open with router

Hello,

As soon as I use my router and try to connect to this website --> www.last.fm Google Chrome says 'sending request' on the left bottom of the page and eventually tells 'Oops! Google Chrome could not connect to www.last.fm'. This started to happen a few days ago.

I don't know what could have initiated this error. Only thing I know is that it has to do something with the wireless router, because I can visit this website when I directly use my cable modem.

I can visit all other websites perfectly.

I tried a different web-browser (Safari, Chrome)
I tried deleting my cookies
I tried the following advice: https://support.google.com/chrome/forum/AAAAP1KN0B0OLuFuuK3tUI/?hl=en&gpf=d/category-topic/chrome/report-a-problem-and-get-troubleshooting-help/OLuFuuK3tUI
I tried the following advice: https://ccm.net/forum/affich-92145-one-certain-site-will-not-load-help
I checked my firewall setting and saw it's not operational

but got the same result.

I have an Apple iMac 10.6.6.

Did someone experience a similar issue?
Does someone have advice that might solve this odd single website-block?