Connectivity issue with backend server

dears, good morning.

 

am facing a strange issue that F5 self cannot reach back-end server with any service even cannot trace-route the server but just can ping it . note that server and F5 in the same subnet and there is no firewall installed in the server and every one can connect normally to the server even from other subnets. in tcpdump i can see f5 sending sync to the server the transmitted then reset

 

09:06:06.054856 IP x.x.x.x.48360 > y.y.y.y:7331: Flags [S], seq 3143605841, win 14600, options [mss 1460,sackOK,TS val 3699543269 ecr 0,nop,wscale 7], length 0 out slot1/tmm1 lis=

 

09:06:07.054257 IP x.x.x.x.48360 > y.y.y.y:7331: Flags [S], seq 3143605841, win 14600, options [mss 1460,sackOK,TS val 3699544269 ecr 0,nop,wscale 7], length 0 out slot1/tmm1 lis=

 

09:06:09.054154 IP x.x.x.x.48360 > y.y.y.y:7331: Flags [S], seq 3143605841, win 14600, options [mss 1460,sackOK,TS val 3699546269 ecr 0,nop,wscale 7], length 0 out slot1/tmm1 lis=

 

09:06:13.054199 IP x.x.x.x.48360 > y.y.y.y:7331: Flags [S], seq 3143605841, win 14600, options [mss 1460,sackOK,TS val 3699550269 ecr 0,nop,wscale 7], length 0 out slot1/tmm1 lis=

 

09:06:18.054289 IP x.x.x.x.48360 > y.y.y.y:7331: Flags [R.], seq 3143605842, ack 0, win 0, length 0 out slot1/tmm1 lis=

 

my f5 OS version 12.1.2 and server OS is Linux installed in vmware