pfsense traceroute loop when only WAN is up (LAN down)

elecen

Hi guys, I am facing the following which is driving me crazy atm.

When I plug the LAN cable to the laptop ethernet (pfsense LAN link UP) pfsense is perfectly reachable.
When I unplug the LAN cable from the laptop (pfsense LAN link DOWN) pfsense is unreachable and according to traceroute appears to enter an endless loop

Traceroute indicates an infinite loop

# Traceroot from Win10 machine
Tracing route to 192.168.108.1 over a maximum of 30 hops

  1    <1 ms    <1 ms    <1 ms  fritz.box [192.168.1.1]
  2     1 ms    <1 ms    <1 ms  pnet.fritz.box [192.168.1.4]
  3     2 ms     1 ms     *     fritz.box [192.168.1.1]
  4     1 ms    <1 ms    <1 ms  pnet.fritz.box [192.168.1.4]
  5     *        *        *     Request timed out.
  6     *        *        *     Request timed out.
  7     *        *       <1 ms  192.168.108.1 ^C

# Traceroute from linux machine
traceroute to 192.168.108.1 (192.168.108.1), 30 hops max, 60 byte packets
 1  fritz.box (192.168.1.1)  1.147 ms  1.417 ms  1.712 ms
 2  pnet.fritz.box (192.168.1.4)  2.525 ms  2.515 ms  2.809 ms
 3  fritz.box (192.168.1.1)  8.567 ms  8.906 ms  9.233 ms
 4  pnet.fritz.box (192.168.1.4)  9.595 ms  9.928 ms  10.133 ms
 5  * * *
 6  pnet.fritz.box (192.168.1.4)  15.337 ms  4.725 ms  7.844 ms
 7  * * *
 8  pnet.fritz.box (192.168.1.4)  9.447 ms  9.913 ms  10.900 ms
 9  * * *
10  pnet.fritz.box (192.168.1.4)  12.723 ms  12.959 ms  13.368 ms
11  * * *
12  pnet.fritz.box (192.168.1.4)  9.185 ms  7.724 ms  7.988 ms
13  * * *
14  pnet.fritz.box (192.168.1.4)  3.911 ms  1.662 ms  1.471 ms
15  * * *
16  pnet.fritz.box (192.168.1.4)  6.107 ms  6.505 ms  6.921 ms
17  * * *
18  pnet.fritz.box (192.168.1.4)  8.331 ms  8.731 ms  9.185 ms
19  * * *
20  pnet.fritz.box (192.168.1.4)  11.620 ms  12.066 ms  12.479 ms
21  * * *
22  pnet.fritz.box (192.168.1.4)  11.204 ms  11.323 ms  9.651 ms
23  * * *
24  pnet.fritz.box (192.168.1.4)  12.192 ms  16.575 ms  14.170 ms
25  * * *
26  pnet.fritz.box (192.168.1.4)  3.468 ms  1.833 ms  1.834 ms
27  * * *
28  pnet.fritz.box (192.168.1.4)  3.497 ms  1.902 ms  2.321 ms
29  * * *
30  pnet.fritz.box (192.168.1.4)  5.711 ms  6.727 ms  7.181 ms

# no ctrl+c here, linux is fast :D

Here's what my simple home network looks like

192.168.1.1 fritzbox (internet gateway, connected to ISP)
pfsense (WAN 192.168.1.4; LAN 192.168.108.1)
network switch (pfsense, fritzbox and pretty much everything is connected to it)
laptop (wifi connected to fritzbox)
desktop (192.168.1.44)
laptop (192.168.1.45)

My pfsense configuration looks like this

Sidenote: I have tried OPNSense with virtually identical configuration with no trouble. Also have OpenWRT in similar setup for different subnet also working with no trouble

Any ideas?