Hi, I have a problem with the phone configuration on the archer VR600v.

I follow this instruction (https://www.tp-link.com/it/support/faq/2360/). On the second line "Registro Indirizzo" is supposed to insert the Outbound proxy. The problem is that the OP that my provider gives me is "d434s1.co.imsw.telecomitalia.it" but when I insert it in "Registro Indirizzo" the last letter is omitted (like I have reached the maximum digit number). Any suggestion?