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DHCP issues on External Interface with ISP

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I have been using UTM for many years now... 6+?  When I first started, there were issues with certain Intel nics when used with DHCP and Cable Modems.

Lately, I have been having problems again.  I have had MANY calls with my ISP, I even went ahead and bought new hardware for my UTM.  Same problem.  I rarely get an IP address from my ISP and when I do, the external interface will only stay "up" for a brief period - and then drop again.

I plugged my "Gateway desktop" directly into my Cable Modem and it ran without an issue for 3 days.  Then I added an ASUS RT-N66 in as a "router".  That ran fine for a week - with A LOT of traffic going through it. 

I add the UTM and BAM!  I am back down again.

My question is - WHERE do I begin to troubleshoot this?  confd logs?  TCPDUMP?  My UTM seems happy to get a DCHP address from my ASUS if I test it that way...  I don't want to bail on Sophos, but I don't know what else to do.  Many years ago, I put an old router between my Cable Modem and my Sophos machine.  I really don't want to do that again.

UTM 9.355-1       

External NIC is an Intel Gigabit PCIe   EXPI9301CT

Quad core i3 with 4GB RAM, 160 GB HDD

Thoughts?  Advice, Similar issues?



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  • 0

    Did you figure out any resolution to this issue?  We're seeing much the same behavior on an Arris with Comcast-provided DHCP.

  • 0 in reply to MichaelOh

    Michael,

    What software level are you at with your Sophos? I assume it's UTM 9, also? I've been running into some weird issues since updating to 9.404 and newer with mine, but I think part of it is related to the 576 MTU I'm getting from Comcast on the external interface. I'm also noticing IPv6 isn't working properly, which kills my in-home streaming as it relies on it in my area. I'm thinking of reloading 9.3 and seeing if that restores the functionality, especially because I'm not having issues when swapping the UTM for my netgear wireless router.

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  • 0 in reply to MichaelOh

    Michael,

    What software level are you at with your Sophos? I assume it's UTM 9, also? I've been running into some weird issues since updating to 9.404 and newer with mine, but I think part of it is related to the 576 MTU I'm getting from Comcast on the external interface. I'm also noticing IPv6 isn't working properly, which kills my in-home streaming as it relies on it in my area. I'm thinking of reloading 9.3 and seeing if that restores the functionality, especially because I'm not having issues when swapping the UTM for my netgear wireless router.

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