The issue is that FPCs is flapped due a high memory consumption and not able to connect to the device via SSH, The FPC flapped at time 2023-03-20 18:13:01, We can't know when the issue started, as the recent messages file not covered before Aug 27 05:30:01,
Important Messages log,
Aug 27 05:30:01 ER1.GDC_SRX.node0 /kernel: rt_pfe_veto: Memory over consumed. Op 8 err 12, rtsm_id 0:-1, msg type 10, veto simulation: 0
Aug 27 05:30:01 ER1.GDC_SRX.node0 /kernel: rt_pfe_veto: free kmem_map memory = (20963328) curproc = rpd
Aug 27 05:32:46 ER1.GDC_SRX.node0 /kernel: rt_pfe_veto: Memory over consumed. Op 8 err 12, rtsm_id 0:-1, msg type 10, veto simulation: 0
Aug 27 05:32:46 ER1.GDC_SRX.node0 /kernel: rt_pfe_veto: free kmem_map memory = (20963328) curproc = rpd
Aug 27 05:32:46 ER1.GDC_SRX.node0 /kernel: rt_pfe_veto: Possible slowest client is fwdd0. States processed - 791174963. States to be processed - 3
Aug 27 05:32:46 ER1.GDC_SRX.node0 /kernel: rt_pfe_veto: Possible second slowest client is fwdd1. States processed - 791174963. States to be processed - 3
Aug 27 06:29:09 ER1.GDC_SRX.node0 /kernel: tcp_timer_keep: Dropping socket connection due to keepalive timer expiration, idle/intvl/cnt: 7200000/75000/8
Aug 27 06:29:09 ER1.GDC_SRX.node0 /kernel: tcp_timer_keep:Local(0x81100001:53860) Foreign(0x8f100001:33010)
Aug 27 06:29:46 ER1.GDC_SRX.node0 /kernel: kmem type ifstat using 313537K, exceeding limit 286720K
Aug 27 06:30:29 ER1.GDC_SRX.node0 /kernel: tcp_timer_keep: Dropping socket connection due to keepalive timer expiration, idle/intvl/cnt: 7200000/75000/8
Aug 27 06:30:29 ER1.GDC_SRX.node0 /kernel: tcp_timer_keep:Local(0x81100001:55390) Foreign(0x8f100001:33010)
Aug 27 06:30:46 ER1.GDC_SRX.node0 /kernel: kmem type ifstat using 313538K, exceeding limit 286720K
Aug 27 06:31:46 ER1.GDC_SRX.node0 /kernel: kmem type ifstat using 313538K, exceeding limit 286720K
Aug 27 06:31:49 ER1.GDC_SRX.node0 /kernel: tcp_timer_keep: Dropping socket connection due to keepalive timer expiration, idle/intvl/cnt: 7200000/75000/8
Aug 27 06:31:49 ER1.GDC_SRX.node0 /kernel: tcp_timer_keep:Local(0x81100001:50126) Foreign(0x8f100001:33010)
Aug 27 06:32:47 ER1.GDC_SRX.node0 /kernel: kmem type ifstat using 313538K, exceeding limit 286720K
All the above messages are repeated on all Message files,
This is a software issue related to PR1528605 which you can view on the following link, https://prsearch.juniper.net/problemreport/PR1528605, Your current software version is JUNOS [20.2R1.10] and this software issue is Resolved in below software versions,
junos:17.3R3-S11 junos:17.4R3-S5 junos:18.1R3-S13 junos:18.2R3-S7 junos:18.2R3-S8 junos:18.2X75-D34
junos:18.2X75-D436 junos:18.2X75-D56 junos:18.2X75-D61 junos:18.2X75-D67 junos:18.3R3-S4 junos:18.4R2-S7
junos:18.4R3-S6 junos:19.1R3-S4 junos:19.2R1-S6 junos:19.3R2-S6 junos:19.3R3-S1 junos:19.4R1-S4
junos:19.4R2-S4 junos:19.4R3-S1 junos:20.1R2 junos:20.1R3 junos:20.2R2-S2 junos:20.2R3 junos:20.3R1-S2
junos:20.3R2 junos:20.3X75-D10 junos:20.4R1 junos:21.1R1