The object name contains more than the maximum number of prefixes. The maximum is 3

Correct four-part table name is server.database.schema.tablename - you have some excess parts there.

Looks like table name is OPC.WriteRequests? If yes, then you have to use brackets: SQL05.ManufacturingPortal.dbo.[OPC.WriteRequests]

But maybe you just have some part of name incorrect?

The reason you are receiving the error is because you are not using a valid name. You appear to be referencing two schemata, dbo and OPC.

The valid syntax is server_name.database_name.schema_name.object_name as referenced on the MSDN article for INSERT.

Remove the incorrect schema and try again.

I was using everything correct still the issue persisted. My command was like below

select * into server.database.schema.table from table2

I resolved it by creating the table in the server first and then used the insert into statement which executed without issues

Create Table...........
Insert into server.database.schema.table  select * from table2

Thanks, Sree