Laptop loses connection to gateway

[abulafia]

Hi, strange behaviour that I have come across on 21.1.5, and not sure where to begin to troubleshoot:

I have one(!) laptop that loses connection to the OPNsense gateway intermittently since a few days:

Setup:

WAN -> Cable Modem -> OPNsense -> Unifi switch - LAN clients / wifi clients

Issue:

My work laptop suddenly loses connection to the gateway: It can still ping all LAN devices, as well as the switch, but no longer access the OPNsense IP (nor WAN of course). A reboot of OPNsense fixes this - for a few minutes and then connection _for this client_ fails again.

All other devices (LAN and wifi) continue to be able to access OPNsense and WAN. So the problem seems to be either in OPNsense or the switch.

How could I narrow down the issue? Is it ...
- related to RSTP issues?
- related to routing (I have the FRR routing plugin installed)?
- related to firewall / shaping (why do the other 192.168.1.0/24 clients have access though)?
- ...?
 -

[allebone]

please check arp table on opnsense during connectivity loss, and if missing entry try adding a static arp entry to see if this brings back connectivity.
Also check arp table on client (less likely to be issue).

[abulafia]

Thanks allebone.

DHCP leases & logfile and ARP table show that a DHCP lease (specifically: the existing DHCP lease!) has been send to, and accepted by, the Windows laptop. It then loses access to OPNsense.

I have setup a static entry and will check tomorrow whether that alleviates the issue.

[allebone]

I mean check the arp table on opnsense side. SSH into the box and check arp table with
arp -a -n

you can add a static arp with
arp -s <IP OF LAPTOP> xx:xx:xx:xx:xx:xx

etc.