canceling statement coming in slave instance

Dear List,

In few of our Slave PostgreSQL machines.

I occasionally encounter below error.

*ERROR: canceling statement due to conflict with recovery*
*DETAIL: User was holding a relation lock for too long*

While investigating online i came to know that this issue can be handled by
below configuration parameters

"max_standby_archive_delay "
"max_standby_streaming_delay"

I have increased the value of both the parameters as per below.

Original values:
"max_standby_archive_delay=30s"
"max_standby_streaming_delay=30s"

Current values:
"max_standby_archive_delay=30s" ----> was increased it to 300s but we did
not get any benefit so we rollback it to original value
"max_standby_streaming_delay=300s"

But still i occasionally encounter the mention issue.

Please note that on Master node we have heavy write operations and these
Slave nodes are geographically distinct on a WAN connection.

Thanks in Advance
Rohit Arora