These depend on what stack you are on.
you can check what stack your are on by:
- Going to trust.marketingcloud.com and entering your MID number
- log into marketing cloud and check the prefix to the url. It would be ssomething eg s7.mc.exacttarget.com would mean you are on the s7 stack
Stack WSDL Link
S1 Instance https://webservice.exacttarget.com/Service.asmx
S10 Instance https://webservice.s10.exacttarget.com/Service.asmx
Sandbox Instance https://webservice.test.exacttarget.com/Service.asmx