Long delay issue for hue bridge listed in 'inbox'

For hue binding discovery, basically, client can trigger it by sending ‘/rest/discovery/bindings/hue/scan’ to openhab servers.

Say I have hue bridge & there’s cable between hue bridge and hub.
Supposedly, upon REST request above ,hue bridge is listed in ‘inbox’. We can see that by either REST API or Habmin.

Say I open page for Habmin to see when hue bridge go into ‘inbox’.
Actually, in most cases, I see hue bridge go into ‘inbox’ very quickly in about 1 or 2 seconds. However, sometimes, I did experience delay as long as around 100 seconds for the hub bridge to go into ‘inbox’.

Have someone experienced this long delay issue for hue bridge discovery as well? Thank you very much.

[follow up]

As the snapshot above,
1 we can see the around 100 seconds delay is from the response from hue hub to the openhab server. (Right after M-search packe)
2 In other words, it is NOT from client send out REST request to openhab.
3 It is NOT from hub binding send out packet to hue bridge as well.

[Notes:] is hue bridge. is openhab server.

Almost same time I saw the response (from hue hub to openhab server) appear on wirehshark, On Habmin, I saw the hue hub come into ‘inbox’.

Does any expert have some idea why I have this long delay for hue bridge come into ‘inbox’? Thank you very much.

Say I have hue bridge & hue lamp.

For same hue bridge, I have done some comparsion experiments for both hue app & openhab.
I never see the long delay issue on hue app for hue bridge discovery while I have it on openhab.

Below is some observation on wireshark.
For hue app,
1 Send out M-search pack.
2 After around 8 seconds, they send ARP broadcast.
3 ARP response back from hue bridge to openhab.
4 hue app start to communicate with hue bridge.

For openhab
1 Send out M-search pack.
2 Wait until M-search response back from hue bridge. It can takes 40s/80s/100s.
3 openhab start to communicate with hue bridge After M-search response pack.

Although I dont know how hue app get the IP of hue bridge,
it seems
1 hue app some other mechnism to do that, NOT only depend on M-search response back.
2 However, openhab hue binding, depend on M-search response back. And that’s cause of the delay.

For hue binding, just by some simple configuration, is it possible to make it work like hue app so that it can get rid of the discovery delay issue?
Can some expert shed some light for that? Thank you very much.

[hue app scenario, ARP broadcast 8s after M-search]

[hue app scenario, NO pack between hue bridge & hue app before ARP broadcast]