Cloud Switches - Disconnection on LAN

Hey everyone.
I have recent deploy 1 CRS326-24G on my companies network. We like it that much that we buy another one, but with 48 ports more specific CRS354-48G, to retire an old cisco.
Unfortunately when I added the second switch I come across various disconnection problems and ping spike despite the servers and workstation are on the same network, that mean not routing between the server is happening.
Also the bandwidth is not that stable.

[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  69.9 MBytes   586 Mbits/sec
[  5]   1.00-2.00   sec  77.9 MBytes   653 Mbits/sec
[  5]   2.00-3.00   sec   105 MBytes   882 Mbits/sec
[  5]   3.00-4.00   sec   103 MBytes   863 Mbits/sec
[  5]   4.00-5.00   sec   102 MBytes   852 Mbits/sec
[  5]   5.00-6.00   sec  89.1 MBytes   747 Mbits/sec
[  5]   6.00-7.00   sec  82.8 MBytes   695 Mbits/sec
[  5]   7.00-8.00   sec  99.9 MBytes   838 Mbits/sec
[  5]   8.00-9.00   sec  89.8 MBytes   753 Mbits/sec
[  5]   9.00-10.00  sec  90.2 MBytes   757 Mbits/sec
[  5]  10.00-10.06  sec  3.62 MBytes   544 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.06  sec   913 MBytes   761 Mbits/sec                  receiver

My physical network configuration is like this:
DGS-1210-28MP >>port24>1G>port1>> CRS354-48G >>port48>1G>port1>> CRS326-24G

At last I have only configured RSTP with root bridge the CRS354, other configuration is some light routing on the CRS326.

Also some ping result

Reply from x.x.x.x: bytes=32 time<1ms TTL=128

Reply from x.x.x.x: bytes=32 time<1ms TTL=128

Reply from x.x.x.x: bytes=32 time=19ms TTL=128

Reply from x.x.x.x: bytes=32 time<1ms TTL=128

Reply from x.x.x.x: bytes=32 time<1ms TTL=128