I have to change the Local IPv4 connection or Interface to the correct IP.
You should not select the particular IPs but either the interface name or unique ID. On Windows you should select the GUID: '{12345678-CCCC-9805-4242-ABCDEF05FD16}'
"Could not listen for incoming connection".
After about 5 - 15 minutes, the Tixati client finally connects properly to peers and downloads. Sometimes lon
Are you sure you have a white IPv4 and
technically can use port-forwarding on your router? Often the ISP is the limitation but IPv6 should work without problems (if allowed on router and firewall).
What is the approximate ratio of incoming/outgoing connections in the peers tab? If there're plenty incoming connections then it should be working fine on your end. The 5-15min delay still sounds like a tracker update delay (announce) or a problem with port forwarding (maybe your peers are at fault).
Tixati announces to trackers every ~30min so if the first connection attempt failed (and you need to change the IP settings for connectivity) then no wonder it takes a lot of time until Tixati retries tracker announcement only after the last timer expires.
Logs: Tixati main window > top-right Question mark > Diagnostics > UPNP/NAT-PMP Log. But I don't think it's useful for your case.