Netgear MR2100 Can't Get 4G Plus Connection

Hi All,

I bought MR2100 AUS set several month ago, at first it will give me around 160-180Mbps download speed. But then its get update to latest firmware NTGX24_10.17.10.00 and wont connect to 4G Plus (4G+) here in Malaysian region. Now it's just get me around 130Mbps during mid night and 30-40Mbps during pick hour.

How to revert back to old firmware because i believe it is the cause. I already push reset button once.

As far as i know, this M2 capable to connect up to 5ca. In my area B1, B3, B7 and B8 are available.