First of all, i have been reading a lot on this forum about this topic, but none really fit my situation and i have not found any good solution for my problem. My situation is actually really simple in the way it's set op. Most things i read here has to do with multiple NICs and/or link balancing. However my setup is [ISP Modem]--[ESX Server with the hardware onboard nic directly connected to the Sophos VM]. This setup worked for ages just fine, but out of nowhere last night somewhere the "internet' stopped working and this morning i saw the dashboard is showing a link error while nothing has been changed on my side.
I have attached a laptop directly to the ISP modem, and then it seems to work and internet is working, but connecting my UTM to it shows the error, even after a reboot of the UTM. I have also rebooted the ISP modem. I don't see anything wierd in the logs, the UTM is getting an IP from the ISP's DHCP server.
I have tried changing the NIC in the ESX server from Static speed to Auto Neg. This did not change anything. So, im actually stuck right now. Considering i did not change anything myself, i would say something on the ISP end must have changed, however, why would the windows laptop work? Any help would be appreciated.
ok, let‘s start step by step. When you connect your laptop, what‘s the gateway you are getting? Write this down. Connect the ESXi server and check , if you can reach this IP from your UTM.
Then we go on.
Mit freundlichem Gruß, Regards from Germany,
New Vision GmbH, GermanySophos Silver-Partner
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What if you just change the MTU back to 1500?
Cheers - Bob
Hi Bob, very good idea, that‘s worth testing.
But shouldn’t the minimum of 576 bytes work in all cases?
Several years ago, a lot of people had strange problems with their ISP's network assigning the External interface an MTU of 576. Just setting it manually to 1500 was the solution. In this case, if making the setting in the UTM doesn't resolve this, I will wonder if there's not an issue with the configuration of VMWare or the vm.
Thank you both for responding. Because of Xmas and NY a delayed response. It turned out the ISP had made some changes in the back-end, which i could not see. Took me a while to find this out. After they changed me back to 'an old platform' everything went alright again.
With kind regards,
What MTU does their DHCP now assign, Peter?
Still 576, just checked.