DT Server keeps asking “want to use system keychain”

Just setting up DT server in dt3 server version today.
Settings in DT is easy and smooth. I also do port forwarding in my router to my DT server computer, and got a valid certificate for HTTPS connection. The DT part is without problem. The problem is whenever I login through safari to DT, the host macOS (hosting the DT server) keeps asking me to enter administrator credentials that “macOS wants to use the “system” keychain”. A simple DT safari login action causes around 10 pop ups on the host macOS, and every browser action causes another round of pop ups.
any clue to solve this problem?

Is your certificate/key in your login keychain or only in the system’s keychain? The login keychain is definitely recommended.