Too few details to pinpoint the root cause of network collisions you are seeing (provide relevant logs, topology with distance between edge swtiches and core switch, total number of connected hosts, ports working speeds, duplex modes, etc.).
Segmenting a network should always a good thing but network collisions could happen also on segments so you need to understand how your network is behaving now (and how it was setup) to understand where is the faulty points (or the offending hosts). There could be really many reasons to provide you here - with few detalis provided - a definitive solution.
I'm not an HPE Employee
below the logs files of 1 of the switches
HP-2920-48G-POE+# show system
Status and Counters - General System Information
System Name : HP-2920-48G-POE+
System Contact :
System Location :
MAC Age Time (sec) : 300
Time Zone : 0
Daylight Time Rule : None
Software revision : WB.15.15.0012 Base MAC Addr : 70106f-7ff3c0
ROM Version : WB.15.05 Serial Number : Info Erased
Up Time : 7 days Memory - Total : 169,755,136
CPU Util (%) : 0 Free : 85,435,400
IP Mgmt - Pkts Rx : 118,011,346 Packet - Total : 6750
Pkts Tx : 193,532 Buffers Free : 5008
Lowest : 4280
Missed : 0
HP-2920-48G-POE+# show logging
Keys: W=Warning I=Information
M=Major D=Debug E=Error
---- Event Log listing: Events Since Boot ----
I 01/01/90 00:00:03 03802 chassis: System Self test started on Master
I 01/01/90 00:00:03 03803 chassis: System Self test completed on Master
I 01/01/90 00:00:06 00061 system: -----------------------------------------
I 01/01/90 00:00:06 00062 system: Member 1 went down without saving crash
information
M 01/01/90 00:00:06 03001 system: System reboot due to Power Failure
I 01/01/90 00:00:06 02759 chassis: Savepower LED timer is OFF.
I 01/01/90 00:00:06 02751 chassis: LEDs for Ports 1-48 configured ON.
I 01/01/90 00:00:06 02712 console: USB console cable disconnected
I 01/01/90 00:00:06 02682 OOBM: OOBM - Enabled globally.
I 01/01/90 00:00:07 00690 udpf: DHCP relay agent feature enabled
I 01/01/90 00:00:07 00118 timep: timep client enabled
I 01/01/90 00:00:07 02637 srcip: TACACS admin policy is 'outgoing interface'
I 01/01/90 00:00:07 02638 srcip: TACACS oper policy is 'outgoing interface'
I 01/01/90 00:00:07 02637 srcip: RADIUS admin policy is 'outgoing interface'
I 01/01/90 00:00:07 02638 srcip: RADIUS oper policy is 'outgoing interface'
I 01/01/90 00:00:07 02637 srcip: SYSLOG admin policy is 'outgoing interface'
I 01/01/90 00:00:07 02638 srcip: SYSLOG oper policy is 'outgoing interface'
I 01/01/90 00:00:07 02637 srcip: TELNET admin policy is 'outgoing interface'
I 01/01/90 00:00:07 02638 srcip: TELNET oper policy is 'outgoing interface'
I 01/01/90 00:00:07 02637 srcip: TFTP admin policy is 'outgoing interface'
I 01/01/90 00:00:07 02638 srcip: TFTP oper policy is 'outgoing interface'
I 01/01/90 00:00:07 02637 srcip: SNTP admin policy is 'outgoing interface'
I 01/01/90 00:00:07 02638 srcip: SNTP oper policy is 'outgoing interface'
I 01/01/90 00:00:07 02637 srcip: SFLOW admin policy is 'outgoing interface'
I 01/01/90 00:00:07 02638 srcip: SFLOW oper policy is 'outgoing interface'
I 01/01/90 00:00:07 02637 srcip: RADIUS admin policy for IPv6 is 'outgoing
interface'
I 01/01/90 00:00:07 02638 srcip: RADIUS oper policy for IPv6 is 'outgoing
interface'
I 01/01/90 00:00:07 00110 telnet: telnetd service enabled
I 01/01/90 00:00:07 00110 telnet: telnetd service enabled
I 01/01/90 00:00:07 00433 ssh: Ssh server enabled
I 01/01/90 00:00:07 00417 cdp: CDP enabled
I 01/01/90 00:00:07 00688 lldp: LLDP - enabled
I 01/01/90 00:00:07 02633 SNTP: Client authentication is disabled.
I 01/01/90 00:00:07 02012 mtm: A non-multicast client: Non-Mcast client Op, is
registered with client ID: 1
I 01/01/90 00:00:08 00066 system: System Booted
I 01/01/90 00:00:08 02550 chassis: Requesting Co-processor OS image location in
flash.
I 01/01/90 00:00:08 02552 chassis: Loading of Co-processor OS image in progress.
I 01/01/90 00:00:09 02553 chassis: Loading of Co-processor OS image complete.
I 01/01/90 00:00:10 03802 chassis: System Self test started on 1-48
I 01/01/90 00:00:16 03803 chassis: System Self test completed on 1-48
I 01/01/90 00:00:16 02555 chassis: Co-processor Ready
I 01/01/90 00:04:12 00076 ports: port 19 is now on-line
I 01/01/90 00:04:12 00001 vlan: DEFAULT_VLAN virtual LAN enabled
I 01/01/90 00:04:22 00119 timep: can't reach time server 10.5.0.1
I 01/01/90 00:04:42 00076 ports: port 20 is now on-line
I 01/01/90 00:04:59 00076 ports: port 21 is now on-line
I 01/01/90 00:05:18 00076 ports: port 22 is now on-line
I 01/01/90 00:05:38 00076 ports: port 23 is now on-line
I 01/01/90 00:06:06 00076 ports: port 24 is now on-line
I 01/01/90 00:06:19 00076 ports: port 25 is now on-line
I 01/01/90 00:06:41 00077 ports: port 19 is now off-line
I 01/01/90 00:06:49 00076 ports: port 19 is now on-line
I 01/01/90 00:07:25 00076 ports: port 26 is now on-line
I 01/01/90 00:07:31 00076 ports: port 27 is now on-line
I 01/01/90 00:07:39 00076 ports: port 28 is now on-line
I 01/01/90 00:07:45 00076 ports: port 29 is now on-line
I 01/01/90 00:07:56 00076 ports: port 30 is now on-line
I 01/01/90 00:08:12 00076 ports: port 31 is now on-line
I 01/01/90 00:08:47 00076 ports: port 18 is now on-line
I 01/01/90 00:17:14 00077 ports: port 18 is now off-line
I 01/01/90 00:17:23 00076 ports: port 18 is now on-line
I 01/01/90 00:24:04 00405 ports: port 45 xcvr hot-swap insert.
I 01/01/90 00:24:04 00450 ports: port 45 mini-GBIC is enabled.
I 01/01/90 00:24:22 00077 ports: port 18 is now off-line
I 01/01/90 00:25:27 00076 ports: port 45 is now on-line
I 01/01/90 00:39:39 00121 timep: changing time
I 07/08/20 13:46:52 00122 timep: Updated time by 963061633 seconds from server
at 10.5.0.1. Previous time was Mon Jan 1 00:39:39 1990. Current
time is Wed Jul 8 13:46:52 2020.
I 07/08/20 14:05:00 00077 ports: port 45 is now off-line
I 07/08/20 14:05:10 00076 ports: port 18 is now on-line
I 07/08/20 15:17:24 00076 ports: port 45 is now on-line
W 07/08/20 15:18:41 00331 FFI: port 19-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 20-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 21-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 22-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 23-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 24-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 25-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 26-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 27-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 28-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 29-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 30-High collision or drop rate. See help.
W 07/08/20 15:18:41 00331 FFI: port 31-High collision or drop rate. See help.
I 07/08/20 15:21:50 00077 ports: port 18 is now off-line
I 07/08/20 15:22:47 00077 ports: port 45 is now off-line
I 07/08/20 15:23:30 00406 ports: port 45 xcvr hot-swap remove.
I 07/08/20 15:23:30 00449 ports: port 45 RJ-45 is enabled.
I 07/08/20 15:23:32 00405 ports: port 45 xcvr hot-swap insert.
I 07/08/20 15:23:32 00450 ports: port 45 mini-GBIC is enabled.
I 07/08/20 15:23:54 00406 ports: port 45 xcvr hot-swap remove.
I 07/08/20 15:23:54 00449 ports: port 45 RJ-45 is enabled.
I 07/08/20 15:24:00 00405 ports: port 45 xcvr hot-swap insert.
I 07/08/20 15:24:00 00450 ports: port 45 mini-GBIC is enabled.
I 07/08/20 15:24:39 00406 ports: port 45 xcvr hot-swap remove.
I 07/08/20 15:24:39 00449 ports: port 45 RJ-45 is enabled.
I 07/08/20 15:24:47 00405 ports: port 45 xcvr hot-swap insert.
I 07/08/20 15:24:47 00450 ports: port 45 mini-GBIC is enabled.
I 07/08/20 15:25:37 00076 ports: port 45 is now on-line
I 07/08/20 15:42:48 00077 ports: port 45 is now off-line
I 07/08/20 15:43:01 00076 ports: port 45 is now on-line
I 07/08/20 15:43:02 00828 lldp: PVID mismatch on port 45(VID 1)with peer device
port 47(VID 63)(1)
I 07/08/20 15:49:03 00076 ports: port 13 is now on-line
I 07/08/20 16:03:09 00077 ports: port 13 is now off-line
I 07/08/20 16:06:02 00077 ports: port 45 is now off-line
I 07/08/20 16:13:17 00076 ports: port 18 is now on-line
I 07/08/20 16:15:24 00076 ports: port 45 is now on-line
W 07/08/20 16:15:24 00332 FFI: port 18-Excessive Broadcasts. See help.
I 07/08/20 16:15:34 00077 ports: port 18 is now off-line
W 07/08/20 16:15:45 00332 FFI: port 45-Excessive Broadcasts. See help.
W 07/08/20 16:18:49 00331 FFI: port 19-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 20-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 21-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 22-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 23-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 24-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 25-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 26-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 27-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 28-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 29-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 30-High collision or drop rate. See help.
W 07/08/20 16:18:49 00331 FFI: port 31-High collision or drop rate. See help.
I 07/08/20 18:00:07 00077 ports: port 45 is now off-line
I 07/08/20 18:00:22 00076 ports: port 45 is now on-line
I 07/08/20 18:00:52 00405 ports: port 46 xcvr hot-swap insert.
I 07/08/20 18:00:52 00450 ports: port 46 mini-GBIC is enabled.
I 07/08/20 18:01:00 00078 ports: trunk Trk1 is now active
I 07/08/20 18:01:00 00076 ports: port 46 in Trk1 is now on-line
I 07/08/20 18:01:22 00079 ports: trunk Trk1 is now inactive
I 07/08/20 18:01:22 00077 ports: port 46 in Trk1 is now off-line
I 07/08/20 18:01:31 00078 ports: trunk Trk1 is now active
I 07/08/20 18:01:31 00076 ports: port 46 in Trk1 is now on-line
I 07/08/20 18:18:10 00076 ports: port 7 is now on-line
I 07/08/20 18:18:34 00077 ports: port 7 is now off-line
W 07/08/20 18:19:05 00331 FFI: port 19-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 20-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 21-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 22-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 23-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 24-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 25-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 26-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 27-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 28-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 29-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 30-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 31-High collision or drop rate. See help.
W 07/08/20 18:19:05 00331 FFI: port 45-High collision or drop rate. See help.
I 07/08/20 20:33:22 00077 ports: port 45 is now off-line
I 07/08/20 20:33:27 00079 ports: trunk Trk1 is now inactive
I 07/08/20 20:33:27 00077 ports: port 46 in Trk1 is now off-line
I 07/08/20 20:33:53 00406 ports: port 45 xcvr hot-swap remove.
I 07/08/20 20:33:53 00449 ports: port 45 RJ-45 is enabled.
I 07/08/20 20:34:09 00078 ports: trunk Trk1 is now active
I 07/08/20 20:34:09 00076 ports: port 46 in Trk1 is now on-line
I 07/09/20 02:19:59 00079 ports: trunk Trk1 is now inactive
I 07/09/20 02:19:59 00077 ports: port 46 in Trk1 is now off-line
I 07/09/20 02:20:38 00078 ports: trunk Trk1 is now active
I 07/09/20 02:20:38 00076 ports: port 46 in Trk1 is now on-line
I 07/09/20 02:21:39 00079 ports: trunk Trk1 is now inactive
I 07/09/20 02:21:39 00077 ports: port 46 in Trk1 is now off-line
I 07/09/20 02:22:12 00078 ports: trunk Trk1 is now active
I 07/09/20 02:22:12 00076 ports: port 46 in Trk1 is now on-line
I 07/09/20 02:22:25 00405 ports: port 45 xcvr hot-swap insert.
I 07/09/20 02:22:25 00450 ports: port 45 mini-GBIC is enabled.
I 07/09/20 02:22:36 00076 ports: port 45 is now on-line
I 07/09/20 02:22:36 00077 ports: port 45 is now off-line
I 07/09/20 02:22:37 00076 ports: port 45 is now on-line
I 07/09/20 02:32:16 00079 ports: trunk Trk1 is now inactive
I 07/09/20 02:32:16 00077 ports: port 46 in Trk1 is now off-line
I 07/09/20 02:32:29 00078 ports: trunk Trk1 is now active
I 07/09/20 02:32:29 00076 ports: port 46 in Trk1 is now on-line
I 07/09/20 02:33:13 00076 ports: port 32 is now on-line
HP-2920-48G-POE+#
the connection are like. each edges swith is connected to core switch via fibre link. in each edges switches poe cameras are connected. in core switch the servers , storage , wotstations are connected.
all the connections are inside the building.
there is not much configuration in each edge switch. all are in default vlan 1 with an ip address
Regards
Biju