The following configs worked for me:
FDB_TLS_VERIFY_PEERS=Check.Valid=0 FDB_TLS_CERTIFICATE_FILE="/etc/foundationdb/fdb.pem" FDB_TLS_KEY_FILE="/etc/foundationdb/private.key" FDB_TLS_CA_FILE="/etc/foundationdb/cert.crt" fdbbackup ...
I can’t remember, but you may have to add sc=0 to the blobstore url like blobstore://access:secret@host:port/route?bucket=bucket_name&sc=0.
More info here.