Watch the screen as you type; the player will probably want leading zeroes (i.e. for '8' type '008'), and will probably not want you to actually type a literal dot. (If the result is a mashup of the old number with the new number, you forgot the leading zeros - try again.)
The typical way to enter a number part is to use up-arrow and/or down-arrow as necessary. As the remote control for the S5100 does not even have number keys, it's not clear to me what/where you're typing. Could you please clarify?
Aside: A 192... number is probably not right for a DNS Server. What I meant (and thought I said) was IF 192.x.x.x is the right number on your network, THEN it's probably 192.168.0.x. I should have (but didn't) also say that while such a number is fairly often correct for a "gateway", it's almost certainly incorrect for a "DNS Server".