When entering a comment here in the forums, like I'm doing now, when I click/tap the link button, under Enter the URL, the field already has "http://" filled in. The overwhelming standard now is https://, and many modern browsers object if you try to follow a link with http:// (or even, depending on security settings, refuse to open it).
Possibly it's time to update it to https:// ?
(I'm pretty sure I've seen that button in other boxes around here, but I can't recall where.)