Unable to Save changes in Upfront

When making just the smallest of changes and then clicking save, after about 40 seconds or more of seeing "Saving" on the screen I then get a message "Error. Your changes cannot be saved." I haven't been able to save just the simplest of changes.

I searched around and found suggestions and as so I have altered the limits within PHP:
upload_max_filesize 256M
post_max_size 256M
memory_limit 256M
max_execution_time 300
max_input_time 300

But none of the above have made a difference.

Please could you help?

Thank you