The server is returning 500 error. And in the logs I see many records like (105: No buffer space available) while connecting to upstream
Tried to restart server : didn't help. Increased the number of sockets : didn't help.
VPS, running Ubuntu 16.04 LTS 64bit (with VestaCP if it is important) apache2 Nginx.
Memory:
total used free shared buff/cache available
Mem: 8192 1688 5237 330 1266 6277
Swap: 0 0 0
Total: 8192 1688 5237
Disk space is also sufficient:
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ploop35701p1 423434036 228973348 173279660 57% /
devtmpfs 4194304 0 4194304 0% /dev
tmpfs 4194304 0 4194304 0% /dev/shm
tmpfs 4194304 8412 4185892 1% /run
tmpfs 5120 0 5120 0% /run/lock
tmpfs 4194304 0 4194304 0% /sys/fs/cgroup
none 4194304 0 4194304 0% /run/shm
inodes:
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/ploop35701p1 52953088 933621 52019467 2% /
What can I do (desperated)?