lost a web address

about six weeks ago I joined a motorcycle organization and entered the login information into our Norton vault. until about 4 weeks ago I could log into it but now it says page unavailable. a google search has the Norton icon next to it as shaded and will not load. I can open any other chapter of the organization but the one I belong to. if I take wifi off my phone I can access it that way but not on my computers. I can access it from other other computers and my phone with wifi turned on. I have contacted the admins and they have said that the site is not under maintenance. the url is, www.il-chapter-z.org.  is their something that can be done to get it back so I can get it back?