[Q] Can't downgrade modem

I have an i747m with a 4.3 bootloader. I rooted and installed custom recovery, and a 4.1.1 rom. But whenever I try to install a modem version lower than 4.3 i get a "no network" symbol. I have even tried wiping everything and using stock 4.1.1 odin images for the i747m but no luck. So far i have tried the following CWM flashable modems from this thread:
[MODEM] Complete Modem List for both I747U & I747M

I747MVLLE8: modem_CWM_I747MVLLE8.zip - 19.42 MB - May 8th, 2012 (original shipped)
I747MLALH1: modem_CWM_I747MLALH1.zip - 19.62 MB - August 1st, 2012
I747MVLLH1: modem_CWM_I747MVLLH1.zip - 19.46 MB - August 1st, 2012
I747MUMALJ1: modem_CWM_I747MUMALJ1.zip - 19.48 MB - October 1st, 2012
I747MUMBLK3: modem_CWM_I747MUMBLK3.zip - 18.97 MB - November 3rd, 2012
I747MVLDLK4: modem_CWM_I747MVLDLK4.zip - 18.92 MB - November 4th, 2012
I747MUMBLL1: modem_CWM_I747MUMBLL1.zip - 18.97 MB - December 1st, 2012
I747MVLDMF1: modem_CWM_I747MVLDMF1.zip - 18.99 MB - June 1st, 2013
I747MVLUEMK5: modem_CWM_I747MVLUEMK5.zip - 19.17 MB - November 5th, 2013

The only one that works is the last one. It's 4.3.

audit13 said:

The 4.3 bootloader requires the latest modern. There is no way to use an older modem. This applies to the i747 too.

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samsung are ****ing assholes