I remember such an error happening to me about a year ago when I was using the search button with long search texts.
So, irfan_pak10, I think it's because of your connection, sometimes it has a problem, but it will be fine soon after
I think we have the same experience, forum was down in my end like 2 days ago, but when I changed to a different ISP, I was surprised I was able to access the site without any problem. Just for FYI of everyone, we have only two ISP in our country and I'm using sim card based internet connection which makes it easy for me to switch anytime.