make sure you are using the latest firmware...I imagine you are using version4, so that would be 4.0.8
can you telnet/ssh to the device when the issue occurs and ping the upstream gateway ?
We certainly have 4.0.8. I haven't tried telnet or ssh, but I can access the GUI and look at of the options there.
That is how we tried a reboot of the device (this did not fix the problem).
Cannot ping outgoing from the 720 until a power cycle.
We have also tried the other obvious things like changing the WAN ethernet cable to no avail.
I will try telnet next time it happens if I am onsite. Often it happens when I am not here and the only remedy is the power cycle.
I would suggest capturing some diagnostics from the unit while the problem is occurring and send them to technical support
system -> help & support -> technical support report -> download ( no full logs )
with this info a diagnosis is possible,
I have talked to one of the McAfee support techs and he suggested downgrading to 4.0.7 (after I sent him the diagnostics from the unit)
We did this a week ago at about 7pm on the Wednesday.
This morning (Thursday) the issue reoccured, however I was able to get things going by disabling the Internet interface and re-enabling it.
Still means getting in a car to attend the site and our remote workers cannot connect.
We will get the logs next time it happens.
Do you have any other ideas in the mean time?
Can you generate a support report when the issue is occurring ?
If so, update the support ticket with the tsr and ask for the case to be escalated to level 3
I thought I should report back on this. We managed to get the warranty updated (the McAfee records had the resellers buy date, not our purchase date and the fault was report inbetween the two dates)
The problem turned out to be a faulty port on the device. When we connected the WAN connection to port B instead of port E, we had no more trouble.
McAfee have now replaced the device.
Thanks for your time and sorry it took so long to put this reply here.