IP address changed and now a lot of websites won't load

[pmosb]

I have done all the DNS things.   That is not the problem.

I have looked for blacklistings for my specific address but that is only for mine (it is not blacklisted), not for adjacent addresses within a group of BT's IP addresses.  It appears the whole group of addresses are blacklisted and that blights specific addresses that are not themselves toxic.   

When I was an EE customer it was most often 95:xxx.xxx.x addresses, whereas the other group allocated to EE were 2.xxx.xxx.x and they did not exhibit the blocking.

So what would be better would be for BT not to allocate IP addresses that have blacklist status.