Look for a setting labeled PTT in setup (F2 at powerup).  That needs to be enabled.

I bought my Inspiron 5570 notebook in July of 2018. I did some research and found that it can be modified/updated so it can run Windows 11. I went into the BIOS and turned on PTT. TPM 2.0 showed up on my Device Manager. under "Security devices".

Hey man, I have a 5570 i5-8250U.

How did you reach the 'PTT' option? where is it located?

Thanks!

Welcome to the Dell Community @gandharjc 

In the BIOS setup under "Security".

Best regards,

U2

NOTE:

Depending on this computer and its installed devices, the items listed in this section may or may not appear.

Done! Part of the TPM Gang now lol. 

I wonder why they don't enable it before sale.. 

Thank you so much anyway

i too have inspiron 5570 but for me it shoes no tpm, can you help me