It takes too long to get IP from the DHCP server,M5300-28G-POE+ ProSafe 24-port

Hi,

I have two stacked M5300-28G-POE+ switch which are connected to the core switch and the core switch is connected to the default gateway. We have a DHCP server. The problem is that when we have a connection to the stacked switches, it takes too long (more than two minutes), to get the ip address for the first time and most of the times, the request is timed out.

But when we are directly connected to the core switch it takes about 5 seconds to get the ip address from the server. after several time (ipconfig /release and renew) we get the ip adn for the second tiime after the first succesful ip it becomes faster (I mean getting ip from DHCP becomes faster for the second release and renew). We are sure that the problem is not from the server itself by testing a different scenario (setting the router as the DHCP server). I am sure that it is not a latency problem. I am afraid that there is something wrong in the configuration. 

I would be grateful if you could give me a solution or an opinion. You can find a summary of the configuration as follows:

network protocol none
network parms 10.26.0.14 255.255.255.0 10.26.0.1
vlan database
vlan 16,1000
vlan name 16 "Access" 
vlan name 1000 "Management" 
vlan routing 1000 1 
exit 
network mgmt_vlan 1000
ip ssh server enable
configure
sntp server "10.26.0.1" 
sntp server "de.pool.ntp.org" 2 
clock timezone 1 minutes 0 
time-range
stack 
member 1 13 
member 2 13 
exit
 
ip name server 10.26.0.1
slot 1/0 18 
set slot power 1/0 
no set slot disable 1/0 
slot 2/0 18 
set slot power 2/0 
no set slot disable 2/0 
ipv6 router ospf 
exit
spanning-tree forceversion 802.1d 
snmp-server sysname "XXX"
snmp-server location "XXX"
snmp-server contact "XXX"
 
 
interface 1/0/1
description 'Management'
vlan pvid 1000
vlan participation include 1000
exit 
interface 1/0/2
description 'Access-VLAN16'
vlan pvid 16
vlan participation include 16
exit 
interface 1/0/3
description 'Access-VLAN16'
vlan pvid 16
vlan participation include 16
exit
 
 
interface 1/0/49
description 'Trunk-Port'
vlan participation include 4-16,32,48,64,80,100,110-111,1000
vlan tagging 1,4-16,32,48,64,80,100,110-111,1000
exit 
interface 1/0/50
no auto-negotiate
speed 10G full-duplex
description 'Trunk-Port'
vlan participation include 4-16,32,48,64,80,100,110-111,1000
vlan tagging 1,4-16,32,48,64,80,100,110-111,1000
exit
 
interface 2/0/1
description 'Management'
vlan pvid 1000
vlan participation include 16,1000
exit
interface 2/0/2
description 'Access-VLAN16'
vlan pvid 16
vlan participation include 16
exit 
interface 2/0/3
description 'Access-VLAN16'
vlan pvid 16
vlan participation include 16
exit
 
interface 2/0/49
no auto-negotiate
speed 10G full-duplex
description 'Switch-Uplink'
vlan participation include 4-16,32,48,64,80,100,110-111,1000
vlan tagging 1,4-16,32,48,64,80,100,110-111,1000
exit 
interface 2/0/50
no auto-negotiate
speed 10G full-duplex
description 'Trunk-Port'
vlan participation include 4-16,32,48,64,80,100,110-111,1000
vlan tagging 1,4-16,32,48,64,80,100,110-111,1000
exit
 
 
interface vlan 1000 
routing
exit

It should be mentioned that I set an static ip for the managment vlan (1000) and vlan 16 gets ip from the server. Furthermore, we have only one uplink from the master switch through port 50 to the core switch and other Trunk ports are reserved for the future use and only we have one trunk from each switch to a third switch. 

here is a picture from the scenario:

stacked models:  M5300-52G3 ProSafe 48-port Gigabit L3 with 10 Gigabit

under the stack model: M5300-52G3 ProSafe 48-port Gigabit L3 with 10 Gigabit

Core switch model: XSM7224S - 24-Port 10G SFP+

Best Regards,

Ar