I'll suggest that you take a look at les-70's
thread on the subject.
I think the VMG8324 has essentially a similar command line set as the VMG1312, so establish either a ssh or telnet connection to the device and see if it responds to an
xdslctl --help command line as follows --
$ xdslctl --help
Usage: xdslctl start [--up] <configure command options>
xdslctl stop
xdslctl connection [--up] [--down] [--loopback] [--reverb]
[--medley] [--noretrain] [--L3] [--diagmode] [--L0]
[--tones <r1-r2,r3-r4,...>] [--normal] [--freezeReverb] [--freezeMedley]
xdslctl configure/configure1 [--mod <a|d|l|t|2|p|e|m|M3|M5|v>] [--lpair <(i)nner|(o)uter>]
[--trellis <on|off>] [--snr <snrQ4>] [--bitswap <on|off>] [--sesdrop <on|off>]
[--sra <on|off>] [--CoMinMgn <on|off>] [--i24k <on|off>] [--phyReXmt <0xBitMap-UsDs>]
[--Ginp <0xBitMap-UsDs>] [--TpsTc <0xBitMap-AvPvAaPa>] [--monitorTone <on|off>]
[--profile <0x00 - 0xFF>|<"8a |8b |8c |8d |12a |12b |17a |30a">] [--us0 <on|off>]
[--dynamicD <on|off>] [--dynamicF <on|off>] [--SOS <on|off>] [--maxDataRate <maxDsDataRateKbps maxUsDataRateKbps maxAggrDataRateKbps>]
[--forceJ43 <on|off>] [--toggleJ43B43 <on|off>]
xdslctl bert [--start <#seconds>] [--stop] [--show]
xdslctl afelb [--time <sec>] [--tones] [--signal <1/2/8>]
xdslctl qlnmntr [--time <sec>] [--freq <msec>]
xdslctl inm [--start <INMIATO> <INMIATS><INMCC><INM_INPEQ_MODE><INM_INPEQ_FORMAT>] [--show]
xdslctl snrclamp [--shape <shapeId>] [--bpshape [bpIndex-bpLevel,]]
xdslctl nlnm [--show ] [--setThld <Thld_Num_Tones>]
xdslctl diag [--logstart <nBytes>] [--logpause] [--logstop] [--loguntilbufferfull <nBytes>] [--loguntilretrain <nBytes>] [--dumpBuf <sizeKb>]
xdslctl ntr [--start [output freq(default is 8000)]] [--stop]
xdslctl info [--state] [--show] [--stats] [--SNR] [--QLN] [--Hlog] [--Hlin] [--HlinS] [--Bits]
[--pbParams] [--linediag] [--linediag1] [--reset] [--vendor] [--cfg] [--webstats]
xdslctl profile [--show] [--save] [--restore]
xdslctl --version
xdslctl --help
$
You would be looking at using a
xdslctl configure --maxDataRate <maxDsDataRateKbps maxUsDataRateKbps maxAggrDataRateKbps> command line.