[SR-Users] Problem with registering softphones

Hello! New user here. I'm testing Kamailio installation in testing environment. SIP domain is reachable, Kamailio itself is working fine yet I have a problem with registering softphones. I've tried 3 sip apps and with only one I am able to register with server. Server itself is "vanilla", no changes made. There is user, domain, pwd defined and nothing else. App that successfully connects is X-Lite, after unchecking "Register with domain and receive calls" and checking "Set outbound as domain". Other apps are: Zoiper, Jitsi. After many "checks" and "unchecks" of literary every option I still can't get them to work with me. I'm looking for any kind of hints as of how to get it to register as well as where may I find kamailio logs?