downgrade ios from 16.09 to 15.7

[sumapaypp88]

this is my router 16.09 ios file

4 462502256 Aug 21 2020 08:59:44.0000000000 +00:00 /bootflash/c1100-universalk9_ias.16.09.05.SPA.bin

i need downgrade  it to c2951-universalk9-mz.SPA.157-3.M8.bin

i have get this ios from other router flash as ftp transfeer to my pc

on i set it to router 1 to downgrade 

the file is is corrupt or is not a valid package.

The problem is that my account is not verified for the ability to download files. Can someone give me a direct download link for

c2951-universalk9-mz.SPA.157-3.M8.bin

Is it possible to install it on any version of the . routers or are there certain versions

[Leo Laohoo · Accepted solution]

Not going to work. 

Look at the filenames of those files, they are totally different.  

• c1100-universalk9_ias.16.09.05.SPA.bin is the firmware for an ISR 1100 router.
• c2951-universalk9-mz.SPA.157-3.M8.bin is the firmware for a 2950 ISR G2 router.

[sumapaypp88]

Is there iOS to be installed on any router? Regardless of the version of the router

[Leo Laohoo]

Depends on the router, yes.