- Reconfiguring/reallocating frequency for OFDM channels without much hardware changes.
- Adding higher frequencies for more OFDM channels/bandwidth. But that's still a maximum of 10Gb/s downstream with 2.5Gbps upstream for a single node (6x192MHz OFDM DS + 4x96MHz US). This is the total bandwidth shared on your node between all the users.
And this is assuming you've upgraded the ol cable network splitter and everything to handle frequency between 1~1800MHz while most of the existing equipment are only good up to 1000MHz or so.
You can estimate your current node capacity by looking at your modem status page (192.168.100.1) and calculate the amount of channels you've got. You can also see if you even have real DOCSIS 3.1 working depending on if it's using the OFDM channel or not.
Judging from the frequencies, the cable network seems to be using 6MHz channels for DS. So each 6MHz channel with QAM256 is around 42 Mbps.
The OFDM channels, or real DOCSIS 3.1 will show its modulation as 'Other' with a lot of correctable error due to the nature the channel setup.
The other only real upgrade they can do is doing an N+0 node split, which means splitting the node and bringing the fibre backhaul closer (ironic isn't it) to the end user without the any (+1) amplifier. Basically reduce the amount of users sharing the same bandwidth.
Besides the bandwidth issue, there's also the problem of maintaining the Coaxial plant/network eg. the errors around 700MHz might be ingress/interference from 700MHz 4G signals (band 28). The upstream/downstream power balance depends on how many splitter the user has. Closer to 0dBmV the better. + or -7 or more might give you problems, you add or remove splitter/attenuator to increase/decrease the power level.
The SNR depends on the line quality (40+db is good, depending on the QAM you might start dropping connection once you go lower than ~35db).
Upstream power depends on the length of the wire and amount of splitters you have again. Anything over 52dBmV might start giving you problems.
Any changes to the wiring/splitter/devices connected might affect all of the above. Your neighbour's unterminated plug might also affect your signal level too.
Which made sense why vodafone asked UFB to not build or compete in their current cable footprint. Because even with DOCSIS 3.1, cable seems unlikely remain competitive in the long term compare to true FTTH.