As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CPDLC SLOW TO SEND RECEIVE MESSAGE. CHECKED SATCOM AND FOUND BITE FAIL ON SAT-PHONE PAGE 2/2. PULLED CIRCUIT BREAKER PER QRH CHECKLIST. GROUNDED - YES. RESET SATCOM SDU CIRCUIT BREAKER AND PERFORMED SATCOM BITE PER B737-9 AMM 23-15-00 BITE SHOWS PASS AC OK FOR SERVICE.