Self-signed certificates cannot be used to authenticate sites.
Base on this, someone accesing one specific device cannot be sure that the device which is accesing belong to the person/company that user thinks it belongs.
To be more precise, someone could be performing a MITM attack in that communication and you couldn't be aware of that.
I am going to close this question as duplicative with https://devcentral.f5.com/s/feed/0D51T00007xnOrhSAE - any further clarification or conversation can happen over there. As a reminder - if Dario or Lidev helped you out please help them out (and others) by upvoting or Selecting As Best.