I Need help regarding Ubuntu 14.04 on original Rock Radxa

I have 3 of the original Rock Radxa units (have had 2 running non-stop as Ubuntu 14.04 servers for 6+ years. They are simply great servers). I used the original Ubuntu server Tom Cubie made available, Ubuntu server 12.04, then later upgraded to 14.04 also as provided by Radxa off their web site. It has been excellent.

They are so good I want to keep using them - I can use rkflashtool to backup the NAND flash mem and if needed restore them. I did it on one this week. To use rkflashtool I use a Dell Optiplex 755 SFF PC running Ubuntu 18.04 and via a USB cable.

My problem now is that apt-get update no longer runs without errors and I can no longer install stuff without errors. (i.e. sudo apt-get install vim).

I have tried sudo apt-get clear and also checked the apt sources.list but am not sure why this is happening.

Has support for Ubuntu on the ARM 3188 chipset been dropped ? - some of my errors seem to relate to accessing a Linaro website and getting expired codes (?).

Is anyone able to run sudo apt-get install (any product) and not get failed access errors ?

Doug M