Issues with backup taken in Mojave while downgrading to Lower os x

My old macair had osx Mojave and there is a time machine backup. I want to downgrade to El Capitan. How to do this? Using an installer disk prepared following the apple support pages does work for instillation of macos. I got El Capitan installed. But file system can not be restored from time machine backup prepared using an upgraded os. How to go about this? Thanks.

@dmahapatra - Sadly, I don’t think there is a way as the file system of Mojave is the newer APFS while El Capitan uses the older HFS+

The only way I can think of requires you to us a second Mac which is running Mojave then connect your backup drive to it. Now using a network to connect the two systems sharing your Mojave’s drives. I think that will work. I haven’t tried but logically it should work.

@danj - But there is something interesting. My old TM backup disk shows macOS Extended Journaled (HFS+) file system and not APFS. In fact disk utility does not show an APFS container for the internal disk. Because I wanted El Capitan I did erase the internal disk formatting it in HFS+. So everything is in HFS+ . Even then the backup volume is not read !

Because of the migration problem in El Capitan I loaded Mojave again. This copy is there in my backup volume. I could load it without changing to APFS format. I could then load all files through TM backup. The system is up with HFS+ format. In this case for the internal disk I don't see an APFS container.

But I sincerely want to downgrade since my system has only 4gb ram and it is definitely slower after the upgrade. I will probably try to get the file system copied through a manual or network transfer that you have suggested. Thank you .