It looks like in countries that don't speak english the norm is router pronounced as 'rooter'... In Portugal I've always heard it pronounced 'rooter' as well, but I don't think it has some particular reason for it to be that way. Probably someone mispronounced it the first time and it became the rule??

Granny Weatherwax: 'You've got to think headology, see? Not muck about with all this beauty and wealth business. That's not important.'

Wyrd Sisters, Terry Pratchett