Cannot connect to Jellyfin (Plex) on LAN

RouterOS Beginner Basics
1

Hello!

I just moved my devices from the ISP router to hAP ax2. I only did the “quick setup”, no other configuration (also because I wouldn’t know where to begin :slight_smile:.

I cannot access Plex or Jellyfin from other devices on LAN anymore, internet acces is fine. Apparently some packets are interpreted as invalid and dropped by firewall rule 10. Disabling this rule allows me to connect as expected.

Here are some logs of rule 10 :

And sniff tool for the same requests:

Any idea why these requests are broken or how to troubleshoot further?
Thanks!

PS: my config:

# 2024-10-17 03:20:39 by RouterOS 7.15.2
# software id = xxxxxxxx
#
# model = C52iG-5HaxD2HaxD
# serial number = xxxxxxxxxxx
/interface bridge
add admin-mac=xxxxxxxxxx auto-mac=no comment=defconf name=bridge
/interface wifi
set [ find default-name=wifi1 ] channel.skip-dfs-channels=10min-cac \
    configuration.country=Italy .mode=ap .ssid="computer mkt" disabled=no \
    security.authentication-types=wpa2-psk,wpa3-psk .ft=yes .ft-over-ds=yes
set [ find default-name=wifi2 ] channel.skip-dfs-channels=10min-cac \
    configuration.country=Italy .mode=ap .ssid="computer mkt" disabled=no \
    security.authentication-types=wpa2-psk,wpa3-psk .ft=yes .ft-over-ds=yes
/interface list
add comment=defconf name=WAN
add comment=defconf name=LAN
/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp interface=bridge name=defconf
/disk settings
set auto-media-interface=bridge auto-media-sharing=yes auto-smb-sharing=yes
/interface bridge port
add bridge=bridge comment=defconf interface=ether2
add bridge=bridge comment=defconf interface=ether3
add bridge=bridge comment=defconf interface=ether4
add bridge=bridge comment=defconf interface=ether5
add bridge=bridge comment=defconf interface=wifi1
add bridge=bridge comment=defconf interface=wifi2
/ip neighbor discovery-settings
set discover-interface-list=LAN
/ipv6 settings
set disable-ipv6=yes
/interface detect-internet
set detect-interface-list=all
/interface list member
add comment=defconf interface=bridge list=LAN
add comment=defconf interface=ether1 list=WAN
/ip address
add address=192.168.88.1/16 comment=defconf interface=bridge network=\
    192.168.0.0
/ip dhcp-client
add comment=defconf disabled=yes interface=ether1
/ip dhcp-server lease
add address=192.168.88.11 client-id=1:xxxxxxxxxxxx mac-address=\
    xxxxxxxxxxxxxxxxx server=defconf
/ip dhcp-server network
add address=192.168.0.0/16 comment=defconf dns-server=192.168.88.1 gateway=\
    192.168.88.1 netmask=16
/ip dns
set allow-remote-requests=yes servers=9.9.9.9,149.112.112.112 use-doh-server=\
    https://dns.quad9.net/dns-query verify-doh-cert=yes
/ip dns static
add address=192.168.88.1 comment=defconf name=router.lan
add address=192.168.88.11 name=computer
/ip firewall filter
add action=accept chain=input comment=\
    "defconf: accept established,related,untracked" connection-state=\
    established,related,untracked
add action=drop chain=input comment="defconf: drop invalid" connection-state=\
    invalid
add action=accept chain=input comment="defconf: accept ICMP" protocol=icmp
add action=accept chain=input comment=\
    "defconf: accept to local loopback (for CAPsMAN)" dst-address=127.0.0.1
add action=drop chain=input comment="defconf: drop all not coming from LAN" \
    in-interface-list=!LAN
add action=accept chain=forward comment="defconf: accept in ipsec policy" \
    ipsec-policy=in,ipsec
add action=accept chain=forward comment="defconf: accept out ipsec policy" \
    ipsec-policy=out,ipsec
add action=fasttrack-connection chain=forward comment="defconf: fasttrack" \
    connection-state=established,related hw-offload=yes
add action=accept chain=forward comment=\
    "defconf: accept established,related, untracked" connection-state=\
    established,related,untracked
add action=drop chain=forward comment="defconf: drop invalid" \
    connection-state=invalid
add action=drop chain=forward comment=\
    "defconf: drop all from WAN not DSTNATed" connection-nat-state=!dstnat \
    connection-state=new in-interface-list=WAN
/ip firewall nat
add action=masquerade chain=srcnat comment="defconf: masquerade" \
    ipsec-policy=out,none out-interface-list=WAN
/ip upnp
set enabled=yes
/ip upnp interfaces
add interface=bridge type=internal
add interface=ether1 type=external
/ipv6 firewall address-list
add address=::/128 comment="defconf: unspecified address" list=bad_ipv6
add address=::1/128 comment="defconf: lo" list=bad_ipv6
add address=fec0::/10 comment="defconf: site-local" list=bad_ipv6
add address=::ffff:0.0.0.0/96 comment="defconf: ipv4-mapped" list=bad_ipv6
add address=::/96 comment="defconf: ipv4 compat" list=bad_ipv6
add address=100::/64 comment="defconf: discard only " list=bad_ipv6
add address=2001:db8::/32 comment="defconf: documentation" list=bad_ipv6
add address=2001:10::/28 comment="defconf: ORCHID" list=bad_ipv6
add address=3ffe::/16 comment="defconf: 6bone" list=bad_ipv6
/ipv6 firewall filter
add action=accept chain=input comment=\
    "defconf: accept established,related,untracked" connection-state=\
    established,related,untracked
add action=drop chain=input comment="defconf: drop invalid" connection-state=\
    invalid
add action=accept chain=input comment="defconf: accept ICMPv6" protocol=\
    icmpv6
add action=accept chain=input comment="defconf: accept UDP traceroute" \
    dst-port=33434-33534 protocol=udp
add action=accept chain=input comment=\
    "defconf: accept DHCPv6-Client prefix delegation." dst-port=546 protocol=\
    udp src-address=fe80::/10
add action=accept chain=input comment="defconf: accept IKE" dst-port=500,4500 \
    protocol=udp
add action=accept chain=input comment="defconf: accept ipsec AH" protocol=\
    ipsec-ah
add action=accept chain=input comment="defconf: accept ipsec ESP" protocol=\
    ipsec-esp
add action=accept chain=input comment=\
    "defconf: accept all that matches ipsec policy" ipsec-policy=in,ipsec
add action=drop chain=input comment=\
    "defconf: drop everything else not coming from LAN" in-interface-list=\
    !LAN
add action=accept chain=forward comment=\
    "defconf: accept established,related,untracked" connection-state=\
    established,related,untracked
add action=drop chain=forward comment="defconf: drop invalid" \
    connection-state=invalid
add action=drop chain=forward comment=\
    "defconf: drop packets with bad src ipv6" src-address-list=bad_ipv6
add action=drop chain=forward comment=\
    "defconf: drop packets with bad dst ipv6" dst-address-list=bad_ipv6
add action=drop chain=forward comment="defconf: rfc4890 drop hop-limit=1" \
    hop-limit=equal:1 protocol=icmpv6
add action=accept chain=forward comment="defconf: accept ICMPv6" protocol=\
    icmpv6
add action=accept chain=forward comment="defconf: accept HIP" protocol=139
add action=accept chain=forward comment="defconf: accept IKE" dst-port=\
    500,4500 protocol=udp
add action=accept chain=forward comment="defconf: accept ipsec AH" protocol=\
    ipsec-ah
add action=accept chain=forward comment="defconf: accept ipsec ESP" protocol=\
    ipsec-esp
add action=accept chain=forward comment=\
    "defconf: accept all that matches ipsec policy" ipsec-policy=in,ipsec
add action=drop chain=forward comment=\
    "defconf: drop everything else not coming from LAN" in-interface-list=\
    !LAN
/system clock
set time-zone-name=Europe/Rome
/system note
set show-at-login=no
/tool mac-server
set allowed-interface-list=LAN
/tool mac-server mac-winbox
set allowed-interface-list=LAN
2

The /16 mask is iffy. That takes over one entire RFC1918 range as a single subnet. If you want a /16, use one of 172.16 thru 172.31.

Since I don’t see .13 in your static DHCP reservation list, I’m going to guess the Plex box is set for /24 (255.255.255.0) That will cause havoc.

3

:heart:
It works! (I have no idea why though). I’ll ask GPT to translate your message to English :slight_smile:)

Edit: (what GPT said, that looks like it might make sense)

Packet Handling Confusion> :

If the /16 device sends packets directly to another device on 192.168.88.x (like your Plex box), the /24 device may get confused because it was expecting those packets to come from the router, not directly from the other device.
This mismatch can lead the router or firewall to mark those packets as “invalid” because the connection doesn’t seem to follow the normal path it expects (since one device is trying to talk directly, while the other expects routing through the gateway).

Edit 2: that’s the default config generated by the Quick Setup… if that is problematic by default, maybe it should be changed?

4

Update: the issue returned today, I cannot access the services on this machine from LAN. I had updated the DHCP config as follows:

I’ll disabling firewall rule ‘drop invalid packets’ temporarily.

Any idea what else could this be?