The ForeignID shouldn't be the full URL, it should just be the slug. So in the box you simply type "help" not a full web address starting with http. 32 characters is plenty for that use case.
ForeignID has a limit of 32 characters. I bet your homepage is not "www.mysite.ru" but "www.MyGreatAndAwesomeCustomHomepage.ru" ;) You could increase the length of the field. But you should do it with a simple plugin so that the field length will not be reset later on. Look at that:…