Sophos Firewall: ISP Gateway Fluctuation

Disclaimer: This information is provided as-is for the benefit of the Community. Please contact Sophos Professional Services if you require assistance with your specific environment.

Overview:
Scenario:
Required information:
What to do:

Overview:

This Recommended Read describes the troubleshooting steps & possible solutions when the ISP gateway is down.

Scenario:

ISP connection goes down.
ISP connection/WAN interface fluctuation.
The WAN interface goes DEAD.

Required information:

How many ISP/WAN connections are there?
Name of the ISP provider?
Are all the WAN ports are fluctuating, or any specific one?
Note down the IP of the interface.
Note down the gateway IP.
Port number?
Is the ISP link directly connected with the Sophos WAN Interface?

What to do:

Step: 1 WAN Interfaces

Check the configuration of the WAN interface.
Check the failover rule of the WAN interface from Interfaces > WAN link manager.
To confirm the WAN interface status, review the dgd.log in /log directory via the advanced shell
Sophos Firewall: SSH to the firewall using PuTTY

Sample Logs

Nonworking logs:

DEBUG Jan 07 18:31:35 [27153]: Ping Result for: 8.8.8.8
DEBUG Jan 07 18:31:35 [27153]: Ping: F
DEBUG Jan 07 18:31:35 [27153]: Current Status [GW(Airtel,Port4)] : Dead
DEBUG Jan 07 18:31:35 [27153]: Sleep for 60 Seconds
NOTICE Jan 07 18:31:35 [27153]: Actiontree, Live to Dead
NOTICE Jan 07 18:31:35 [27153]: Actiontree, executing: Live_To_Dead @Airtel

Working logs:

DEBUG Jan 07 18:32:35 [27153]: Initiating Ping: 8.8.8.8
DEBUG Jan 07 18:32:35 [27153]: GW (Airtel, Port4) : Waiting for reply
DEBUG Jan 07 18:32:35 [27153]: Success, Retrying(1) Ping : 8.8.8.8
DEBUG Jan 07 18:32:35 [27153]: GW (Airtel, Port4) : Waiting for reply
DEBUG Jan 07 18:32:35 [27153]: Current Status: Dead
DEBUG Jan 07 18:32:35 [27153]: Ping Result for: 8.8.8.8\
DEBUG Jan 07 18:32:35 [27153]: Ping: S
DEBUG Jan 07 18:32:35 [27153]: Current Status [GW(Airtel,Port4)] : Live
DEBUG Jan 07 18:32:35 [27153]: Sleep for 60 Seconds
NOTICE Jan 07 18:32:35 [27153]: Actiontree, Dead to Live
NOTICE Jan 07 18:32:35 [27153]: Actiontree, executing: Dead_To_Live @Airtel

As we can see from the output, the Sophos WAN interface fails to ping the defined failover IPs, and then the WAN interface is detected as dead.
Try to ping the gateway IP of the specific ISP link and check the connectivity by pinging the gateway IP.
Make sure the IP/subnets aren't clashing with other interfaces.

Note:

Keep the gateway address or the global DNS address (8.8.8.8) in the failover rule as a best practice.
While creating the failover rule with two IPs(ISP gateway and global DNS), always prefer to choose the "OR" condition instead of "AND," so Sophos would have redundancy in case of either IP failure.

To get more clarity on failover conditions, refer to the following: Configure gateway load balancing and failover

Step: 2 Negotiation Settings

Review the negotiation settings of the WAN interface using the below command. Use the respective port number below to get the specific output.

SFVUNL_SO01_SFOS 19.5.2 MR-2-Build624# ethtool Port1
Settings for Port1:
Supported ports: [ ]
Supported link modes: Not reported
Supported pause frame use: No
Supports auto-negotiation: No
Supported FEC modes: Not reported
Advertised link modes: Not reported
Advertised pause frame use: No
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: Unknown!
Duplex: Unknown! (255)
Port: Other
PHYAD: 0
Transceiver: internal
Auto-negotiation: off
Link detected: yes
SFVUNL_SO01_SFOS 19.5.2 MR-2-Build624#

If auto-negotiation is disabled, validate with the ISP provider for best practice or specific reason to keep it disabled. We suggest it should be enabled so Sophos can detect the negotiation change and adjust accordingly.
If the link is detected as "No," please understand how the ISP link is connected to the Sophos WAN interface. We suggest terminating the unmanaged switch between the ISP modem and Sophos WAN interface to ensure the negotiation change is broadcast to both devices.
Further, to cross-check the physical connectivity of the Sophos ports and cabling:

Use the below command in a frequency of a couple of minutes to validate the cabling issues. Please use the respective port number in the below command to get the specific output.

Instance 1:

SFVUNL_SO01_SFOS 19.5.2 MR-2-Build624# ifconfig Port1
Port1 Link encap:Ethernet HWaddr FA:16:3E:4E:11:2D
inet addr:192.168.53.165 Bcast:192.168.53.255 Mask:255.255.255.0
inet6 addr: fe80::f816:3eff:fe4e:112d/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1450 Metric:1
RX packets:688036 errors:548 dropped:88746 overruns:0 frame:0
TX packets:24 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:71195321 (67.8 MiB) TX bytes:2696 (2.6 KiB)

Instance 2:

SFVUNL_SO01_SFOS 19.5.2 MR-2-Build624# ifconfig Port1
Port1 Link encap:Ethernet HWaddr FA:16:3E:4E:11:2D
inet addr:192.168.53.165 Bcast:192.168.53.255 Mask:255.255.255.0
inet6 addr: fe80::f816:3eff:fe4e:112d/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1450 Metric:1
RX packets:688036 errors: 567 dropped: 88863 overruns:0 frame:0
TX packets:24 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:71195321 (67.8 MiB) TX bytes:2696 (2.6 KiB)

As we can see in the output, the drops and errors are increasing. Here, we should consider the cable is faulty, and changing the cable would help.
Please make sure that the MTU/MSS settings of the interface are configured as per the requirement or suggested by the ISP.

Step: 3 ARP

It could be possible that the ISP gateway is losing the ARP of the firewall WAN IP, which might cause the WAN link to be dead.
At the time of the issue,
- Either, we can do ARP ping via console using the below steps:
  - Take the SSH session.
  - Select option 4 > Console.
  - Run the command --> system diagnostics utilities arp ping source <WAN_IP> interface <WAN Interface> <gateway IP>
  - (e.g., system diagnostics utilities arp ping source 192.168.10.10 interface Port4 192.168.10.1)
  - This will force ARP updates to the WAN interface.
- Or, you can do ARP ping via Advance shell using the below steps:
  - Take the SSH session.
  - Select option 5 > option 3 > Advance Shell
  - Run the command --> arping -I Port1 <gateway IPADDRESS>
Alternatively, we can open the interface and hit save (without making any changes) to trigger the ARP request.
If the issue still occurs after triggering the ARP ping manually, please log a support case with all the above information to investigate the issue further - support.sophos.com.

Updated Links to latest
[edited by: Raphael Alganes at 2:20 PM (GMT -8) on 14 Nov 2024]

Parents

Partha Goswami over 1 year ago

I have same issue, with Home version of firewall and ARP system diagnostics utilities arp ping source is worked for me with Airtel static IP router running bridge mode, How to open case for Home version?
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Raphael Alganes over 1 year ago in reply to Partha Goswami

Hello there,

Good day and thanks for reaching out to Sophos Community

Where specifically you are having issues with? is running  system diagnostics utilities arp ping source <WAN_IP> interface <WAN Interface> <gateway IP> on Step 3 of the Recommended Read does not work with your encountered issue? could you elaborate more about your issue and setup? Thanks

Unfortunately, limitations of running a Home version does not come with Support from the Technical Team  Sophos Firewall Home

Many thanks for your time and patience and thank you for choosing Sophos.

Cheers,

Raphael Alganes
Community Support Engineer | Sophos Technical Support
Sophos Support Videos | Product Documentation  |  @SophosSupport | Sign up for SMS Alerts
If a post solves your question use the 'Verify Answer' link.
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Partha Goswami over 1 year ago in reply to Raphael Alganes

if i keep running this system diagnostics utilities arp ping source <WAN_IP> interface <WAN Interface> <gateway IP> ISP is working fine with Bridge mode in router otherwise its falling within 10-20min
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JWCLT over 1 year ago in reply to Partha Goswami

We had to replace our XGS3300. Sophos couldn't figure out what was wrong. Once replaced - we no longer suffer the random internet drops that would recover once a diagnostic ping was run.
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Partha Goswami over 1 year ago in reply to JWCLT

I am using Software version, for investication purpose i would like to inform you sophos utm9.0 has no issue like this, its work perfectly. even i tried sonicwall without any issues
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JWCLT over 1 year ago in reply to Partha Goswami

Oh, I was certain it wasn't a hardware issue - but since Sophos couldn't resolve it, the only thing we could do was replace. We did a backup/restore to the new hardware and it's been working flawelessly. So while it had to be software, it was something in the unit that a backup/restore didn't bring over.
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Partha Goswami over 1 year ago in reply to JWCLT

i see its 100% software issues.
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Partha Goswami over 1 year ago in reply to JWCLT

i see its 100% software issues.
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Partha Goswami over 1 year ago in reply to Partha Goswami

i am planning to buy one Hardware appliance today, but after facing this issues, i am not going to buy.. it
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Sanjeev Jalotia 11 months ago in reply to Partha Goswami

I have facing the issue in the secondary lease line gateway frequently up and down. I have check with our secondary lease line provider they said their end everything is working fine. And the this issue started from 19 Jan 2024 at 5:30 pm to till time. Please confirm there is problem with sophos end.
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