Hi @amaro and @Annemarie_Stolp - many thanks for flagging this issue.
I've just tested the Registry on a couple of computers in our office and it seems to be accessible for me. I also checked the DNS records around the world which are showing as OK for all locations (except unknown issues in Turkey and Malaysia).
Would you be able to post a screenshot of the problem and any diagnostics that you have done to determine this could be a DNS problem?
I'm also adding @ckraft to this thread. Chris is our account manager at Viderum, who supply and manage the IATI Registry on our behalf.
Chris, would you be able to take a look into this?