Need help on DSL-2870B VDSL2+/ADSL2+ modem

Broadcom doesn't sound promising.

RAM capacity is usually specified in bits, 1gbit = 128MB.

can you post the boot log, and if available, the output for lspci.

I assume this is the device ?

if you're in UK, this might be a cheap alternative For Sale (UK) : 2x Bt Hub5 with OpenWrt installed