Your MySQL memory footprint is just too much for the VPS, you have set it to use max 82% of the entire server memory – this is way too much, your system doesn’t have enough resources to perform its duties.
You need to reduce it to at least 50-60%, not more.
For example it looks like you don’t really use InnoDB so you’re wasting memory by allocating memory to the engine you don’t use. I’d disable it completely, at least for the time being or reduce its memory usage to lower values.
If you can post your current my.cnf file I can be more specific in recommendations but based on your previous mysqltuner results:
Your Query cache efficiency is only 27.3%, you need to increase the size of Query cache.
myisam_sort_buffer_size is currently 512M, that is way too much. Make it 4 or 8M and see how it goes.
Key buffer used: 18.4% (24M used / 134M cache), needs to be decreased you’re wasting 110M, so make it like 50M, and run another test to see the usage %. Amount of USED should be close to TOTAL cache, using example above, it would (44M used / 50MB cache).
table_open_cache increase to 800.
try to increase both: tmp_table_size and max_heap_table_size to say to 48M and see the results and watch the overall memory footprint size, remember it should not exceed 50-60% of total server memory.