Your SUT is likely to have some form of verification mechanism which checks user session by verifying parameter(s).
Well-behaved test should do exactly what real browser does, to wit:
- Open login page
- Perform login
- Open dashboard
and your job is to ensure that requests which are being triggered by JMeter are 100% match to the requests which are being sent by the real browser.
Try adding HTTP Cookie Manager to your Test Plan, if your SUT checks the cookie - that should be enough. If not - most probably you will need to perform correlation - the process of extracting dynamic parameters from previous response using JMeter Post-Processors, saving them into JMeter Variables and replacing hard-coded (recorded) values with these variables.