I had the same problem -- 403 forbidden message -- starting Sunday. I contacted Dennis Glazener and it has been resolved. (Thankfully!)
It appears, at least in my case, to be a combination of events. In an effort to prevent access to ALR by spammers, a range of IP address prefixes were blocked. I contacted Verizon FIOS (my internet provider) and in addition to providing me with my router's current IP address, they explained that my router will cycle through a variety of IP addresses on a random schedule.
So, some combination of my then-current IP address prefix and the IP address prefixes being blocked resulted in my access being blocked.
My suggestion is to contact Dennis Glazener with your IP address.
Bill