For some reason I can't seem to be able to follow anyone on mastodon.social. Usually when I follow someone from another instance, it pops up the authentication window, but there it asks to login or copy and paste the link to the profile, which doesn't do anything different.
@ivan instead of using that remote follow option, try pasting their @username@instance into the search bar and following from there.
@ivan @jonbro more than anyone else they are straining under the load. I expect that's a part of it.