Thanks for the help , sorry could not answer back earlier, had to work . I have got a vpn but the software is not installed and no settings put into netduma. I had checked my other devices laptop etc before I had the new hg612 modem and they were all showing the same speeds as my main computer , about 8-10 meg.
At your suggestion I thought I would check them again and the speeds were 24 meg on them, working great. As my speeds were ok with the new openreach modem and my other devices I rechecked the ethernet lead going to my computer , was all ok , tried a different lead to be sure still the same problem. I have software installed on my computer reboot restore rx pro , which enables me to quickly," in seconds" restore to a previous checkpoint. So I restored to mid May checkpoint and checked the speed test and the speeds are back up to 24 meg.
There must have been something in some software/operating system which buggered it up. Never had anything like that happen before. When I used the speed test I tried multiple browsers , chrome , internet explorer, edge etc. and they were all showing low speeds so I do not know what had kicked in to affect all of them. Thanks for mentioning to check the other devices again ,it put me on the right path. Hopefully if someone else has the same problem it might help them too. Thanks again mate , HAVE A GREAT DAY!!