Hello,
Did you check that the service is alive? (CSS# show service summary)
Did you check that the CSS is showing service hits for that content rule? (CSS# show summary) when you are doing requests?
If the users are the ones that are opening the connections, please change the group configuration:
group web
vip address 10.102.1.28
add destination service server52
add destination service server53
add destination service server54
add destination service server55
active
After trying all above, if you keep having the problem, the best way to know what is happening is get simultaneous captures, in the switch(s) where the CSS is directly connected, and you will see the CSS receiving the traffic, and forwarding the traffic to the backend servers.
You will confirm or at least you will see if the CSS is not the problem.
- Rodrigo.