I have no clue how you want to retrieve this host header information via tcpdump. This is what I tried:
sudo tcpdump -i any port 3002 -n
tcpdump: data link type LINUX_SLL2
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
18:48:22.705580 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 3885193030:3885197134, ack 3982702858, win 11, length 4104
18:48:22.705586 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 4104:8208, ack 1, win 11, length 4104
18:48:22.705590 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 4104, win 1163, length 0
18:48:22.705592 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 8208:12312, ack 1, win 11, length 4104
18:48:22.705596 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 12312, win 1162, length 0
18:48:22.705601 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 12312:16416, ack 1, win 11, length 4104
18:48:22.705606 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 16416:20520, ack 1, win 11, length 4104
18:48:22.705609 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 20520, win 1169, length 0
18:48:22.705614 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 20520:24624, ack 1, win 11, length 4104
18:48:22.705619 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 24624:28728, ack 1, win 11, length 4104
18:48:22.705621 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 28728, win 1170, length 0
18:48:22.705626 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 28728:32832, ack 1, win 11, length 4104
18:48:22.705631 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 32832:36936, ack 1, win 11, length 4104
18:48:22.705636 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 36936:41040, ack 1, win 11, length 4104
18:48:22.705641 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 41040:45144, ack 1, win 11, length 4104
18:48:22.705650 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 45144:49248, ack 1, win 11, length 4104
18:48:22.705656 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 49248:53352, ack 1, win 11, length 4104
18:48:22.705661 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 53352:57456, ack 1, win 11, length 4104
18:48:22.705663 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 53352, win 1167, length 0
18:48:22.705669 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 57456:61560, ack 1, win 11, length 4104
18:48:22.705673 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 61560, win 1166, length 0
18:48:22.705674 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 61560:65664, ack 1, win 11, length 4104
18:48:22.705679 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 65664:69768, ack 1, win 11, length 4104
18:48:22.705684 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 69768, win 1165, length 0
18:48:22.705684 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 69768:73872, ack 1, win 11, length 4104
18:48:22.705690 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 73872:77976, ack 1, win 11, length 4104
18:48:22.705693 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 77976, win 1164, length 0
18:48:22.705697 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 77976:82080, ack 1, win 11, length 4104
18:48:22.705702 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 82080:86184, ack 1, win 11, length 4104
18:48:22.705705 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 86184, win 1171, length 0
18:48:22.705710 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 86184:90288, ack 1, win 11, length 4104
18:48:22.705715 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 90288:94392, ack 1, win 11, length 4104
18:48:22.705717 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 94392, win 1172, length 0
18:48:22.705722 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 94392:98496, ack 1, win 11, length 4104
18:48:22.705727 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 98496:102600, ack 1, win 11, length 4104
18:48:22.705732 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 102600:106704, ack 1, win 11, length 4104
18:48:22.705738 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 106704:110808, ack 1, win 11, length 4104
18:48:22.705747 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 110808:114912, ack 1, win 11, length 4104
18:48:22.705752 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 114912, win 1169, length 0
18:48:22.705752 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 114912:119016, ack 1, win 11, length 4104
18:48:22.705757 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 119016:123120, ack 1, win 11, length 4104
18:48:22.705762 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 123120, win 1170, length 0
18:48:22.705763 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 123120:127224, ack 1, win 11, length 4104
18:48:22.705769 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 127224:131328, ack 1, win 11, length 4104
18:48:22.705771 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 131328, win 1170, length 0
18:48:22.705776 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 131328:135432, ack 1, win 11, length 4104
18:48:22.705782 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 135432:136325, ack 1, win 11, length 893
18:48:22.705786 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 136325, win 1169, length 0
18:48:23.331467 lo In IP 127.0.0.1.43490 > 127.0.0.1.3002: Flags [P.], seq 136325:137168, ack 1, win 11, length 843
18:48:23.331485 lo In IP 127.0.0.1.3002 > 127.0.0.1.43490: Flags [.], ack 137168, win 1184, length 0
Error while using Grafana after several minutes:
I already shared my Nginx configs above.
And you should also have the HAR files from Firefox. See my first post.