[Satellite6] Discovery provisioning via external Capsule failed after kexec, discovery UI shows there is no available IPv4

Issue

• Discovery provisioning failed after kexec, discovery UI shows there is no available IPv4
• Capsule proxy.log shows:

2021-04-13T16:51:10 3bec8d81 [I] Started POST /create 
2021-04-13T16:51:11 3bec8d81 [E] Discovery failed, code 422, reason: resource have no errors  
2021-04-13T16:51:11 3bec8d81 [I] Finished POST /create with 500 (1455.9 ms)
2021-04-13T17:12:37 0a7f49f8 [I] Started POST /create 
2021-04-13T17:12:38 2e4ee085 [I] Started POST /PXELinux/00:01:03:04:05:06 
2021-04-13T17:12:38 2e4ee085 [I] Finished POST /PXELinux/00:01:03:04:05:06  with 200 (1.6 ms)
2021-04-13T17:12:39 2e4ee085 [I] Started POST /iPXE/00:01:03:04:05:06  
2021-04-13T17:12:39 2e4ee085 [I] Finished POST /iPXE/00:01:03:04:05:06  with 200 (0.74 ms)
2021-04-13T17:12:39 2e4ee085 [I] Started POST /fetch_boot_file 
2021-04-13T17:12:39 2e4ee085 [I] Finished POST /fetch_boot_file with 200 (4.98 ms)
2021-04-13T17:12:39 2e4ee085 [I] Started POST /fetch_boot_file 
2021-04-13T17:12:39 2e4ee085 [I] Finished POST /fetch_boot_file with 200 (1.06 ms)
2021-04-13T17:12:39 121a1b63 [I] Started PUT /10.1.2.3/power/kexec 
2021-04-13T17:13:37 0a7f49f8 [E] Net::ReadTimeout                  <=================================
2021-04-13T17:13:37 0a7f49f8 [I] Finished POST /create with 500 (60114.62 ms)
2021-04-13T17:14:46 121a1b63 [E] Connection timed out - connect(2)     <=================================