DHCP client/ARP storm

denys

Hi All,
I am new to pfsense, tried to configured it for a replacement of the old gateway and faced the following issue.
If dhcp server is enabled on LAN a client (windows 10 laptop) could connect to it, has internet, but after some random time starts to send multiple arp who-has requests, trying to scan the whole 192.168.0.0/16 network. This after some time causes network problems.
If the same laptop is using one of alternative dhcp servers running on linux machines everything works fine.

The details of the pfsense configuration are:
LAN: ip 192.168.76.39/16 , virtual ip 134...*/25:

lagg0.4090: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
description: WAN
options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
ether 00:08:a2:12:85:d0
inet6 fe80::208:a2ff:fe12:85d0%lagg0.4090 prefixlen 64 scopeid 0x18
inet 134.xxx netmask 0xffffffe0 broadcast 134.xxx
groups: vlan
vlan: 4090 vlanpcp: 0 parent interface: lagg0
media: Ethernet autoselect
status: active
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

lagg0.4091: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
description: LAN
options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
ether 00:08:a2:12:85:d0
inet6 fe80::208:a2ff:fe12:85d0%lagg0.4091 prefixlen 64 scopeid 0x19
inet 192.168.76.39 netmask 0xffff0000 broadcast 192.168.255.255
inet 134.zzz netmask 0xffffff80 broadcast 134.zzz
groups: vlan
vlan: 4091 vlanpcp: 0 parent interface: lagg0
media: Ethernet autoselect
status: active
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

client gets ip 192.168.243.8/16
alternative dhcp server has ip-s in 134 and 192 networks, is a gateway for dhcp clients and uses LAN virtual ip as a gateway.

The device running pfsense is netgate 7100 1U, pfsense v. 21.05.2.

I would really appreciate any help or hints for this!