I’ve been using this forum for years now with no problem using an iPad.
I just got a new iPhone and wanted to login with that and I put in my username and
password and it tells me that there’s "No such name or password" something to that effect.
I tried that many times.
Any suggestions?

There's no difference between logging in with an ipad or an Iphone. Your password is case sensitive. Make sure you enter it that way.