We had a Fortinet 110C in place for several years with our Comcast ISP Cable Modem connection. We replaced the 110C with a new 200D. Within several days the Comcast connection began to fail. We observed that the modem would actually reboot. Here's a list of things we've tried so far but we're still having problems.
- Replaced all power cables
- Replaced all network cables
- Ensured both devices are on UPS protection
- Comcast gave a new modem. No change
- Fortigate support tickets. Nothing definitive from them
- Turned off all non-essential UTM features on the 200D
- Numerous support tickets with Comcast and elevated ticket to District Manager
- Put the original 110C back in place. No problems with it
- RMA'd the original 200D for a new one and installed. Issues continue
We're running low on options. The last couple of things we plan to try are using a hard-coded connection speed on the Fortigate of 100Mb/Full. The auto-negotiate is 1000Mb.
We're also considering loading the 200D with older 5.2 firmware.
I have a suspicion that the 200D is sending some amount or type of data out the WAN that the Comcast modem can't handle and this is causing it to reboot but I need some method or information to support that.
Please let me know if you have any experience with this type of issue or suggestions. We've been fighting with this for several months now.
Thanks,
Troy Taylor