Unable to tunnel traffic in passthrough mode (RUT241)

[LMH_Olsen]

Hello All
First post here, as I am experiencing som issues with the RUT241 we bought here at my working place.

Context: our ISP is phasing out copper-based landlines
all ADSL and similar connections will be removed over the next year or so.
They have announced they will no longer repair cable faults
and instead offer 5G solutions to affected customers.

we have started to investigate our own cellular modem solutions with external antennas
as some of our remote locations are housed in metal containers and internal antennas do not work.

the setup is as follows: hardware firewall on remote site establishes a IKEv2 site-to-site VPN tunnel to a central site.
SIM card uses a custom APN to provide fixed IP address through DHCP (fixed lease).

my changes to settings in RUT241:
changed password
changed auto APN to custom APN
changed net>wan>mob1s1a1 from NAT to passthrough for connected firewall to get public IP

test results (same SIM card in all the tests with cellular modems):

1. connected via ADSL landline (ISP cable modem)
   receives public IP through DHCP
   establishes site-to-site VPN tunnel, connection possible both directions through the tunnel
   outside interface of the firewall reachable from internet (not through the VPN tunnel)

2. connected via Z+X+L 5G modem (passthrough mode)
   receives public IP through DHCP
   establishes site-to-site VPN tunnel, connection possible both directions through the tunnel
   outside interface of the firewall reachable from internet (outside of the the VPN tunnel)
   (not useful as it has internal antenna, not optimal in a metal container, see above)

3. connected via RUT241 (passthrough modem)
   receives public IP through DHCP
   establishes site-to-site VPN tunnel, connection only possible from remote to central through the tunnel
   entering MAC address of connected firewall does not help
   when I disable bridge mode on the LAN interface the connection starts to work in both directions for about 10 seconds then dies
   outside interface of the firewall not reachable from internet

4. connected via RUT241 (bridge mode)
   receives public IP through DHCP
   establishes site-to-site VPN tunnel, no connection in either direction through the tunnel
   outside interface of the firewall not reachable from internet
   also RMS does not work when in bridge mode…

Summary: the VPN tunnel works fine when connected through ADSL landline and through competitors 5G Modem
but not through the RUT241 (with the same SIM card as is in competitors modem), with various symptoms depending on passthrough or bridge mode.

am I doing something wrong and maybe not understanding the way the RUT241 is supposed to work? Any help is appreciated, thanks

[anon65719490]

Hello,

Thank you for reaching out. In this case, to assist you effectively, we’ll need to continue this process privately, because sensitive/publicly unsharable information needs to be gathered. You should find a support request form in the inbox of the email address you used for your forum registration. Kindly fill out the form, and please reference Ticket ID: 14480 when submitting it. Once the form is completed, we’ll contact you directly via email to investigate the issue in detail and help work towards a solution.

Best regards,

[LMH_Olsen]

thank you, email sent