What do the different levels of INP mean? What do the numbers correspond to for the interleave depth? My IP profile has increased by changing to the Huawei modem anyway by at least 3Mb.
INP values tell the modem how much protection against Impulse Noise is required; it is measured in the number of symbols (a symbol lasts one four-thousandth of a second, and has a variable number of bits: if tone 1603 has bit-loading of 7, then 1 symbol is 7 bits. An INP of 3 would want protection for 21 bits, on that tone anyway.
In pre-G.INP days, a value of 3 was "low" interleaving, and a value of "4" was high interleaving; recently, however, a greater variety of values has been seen (and G.INP activation comes with values > 40). You would tend to see depths of 1,000 or more.
The other parameter that matters is "delay", which indicates how many milliseconds of additional latency are allowed to be used. delays of 8ms and 16ms are common; if DLM has intervened on both upstream and downstream, then the delays are accumulative.
In pre-G.INP configurations, the modem would respond by making use of FEC (to correct any errors) and interleaving (to spread data around, so that noise bursts affect different blocks of data. With G.INP in place, expect to see FEC and interleaving still in use, but the overheads they employ are considerable reduced (depths less than 64, delays less than 1ms)
I'll try find the latest firmware and flash that when I get a chance.
It is probably worth using B030SP08, which works with G.INP.
Anything earlier than B030 seems to not like G.INP - and can end up with slower speeds and even higher latencies.