When you are debugging a failing tunnel on your FPR2130 (7.2.5), search for error debug logs with messages like PSK INVALID, INVALID_ID_INFO, or NO_PROPOSAL_CHOSEN because these are usually indicative of Phase 1 setting mismatches like encryption, hashing, DH group, or pre-shared keys. Ensure that both peers have the same ISAKMP policies and authentication methods and search for stuck states like MM_WAIT_MSG that might be indicative of misconfigurations. Firepower Management Center (FMC) can simplify diagnostics by offering human-readable VPN event logs under Analysis > Connections > VPN that provide more insight into issues like parameter mismatches or negotiation failures. Cisco TAC or Firepower-specific troubleshooting guides may be your best resource for exact and version-specific guidance.
Shuvodip Roy