188.8.131.52 & 184.108.40.206 are two main sources + A few tester machine IPs
VIP is 220.127.116.11
Pool members are 18.104.22.168 & 22.214.171.124 - Round Robin + Source Address Persistence
When pool members are recycled / rebooted, traffic sticks to single node.
Clearing persistence record for the VIP fixes the issue, but any 2020 solution ?
If it's http based traffic you can try using cookie persistence. You'll need to have an http profile on the virtual server.
If traffic is not session based, you might try taking out persistence all together.
If neither of those are possible, then you might try reducing the persistence timeout to a value just above the application's session timeout.
Hope that helps.