Charter Spectrum → [HSI] Arris TM1602 Modem and Dlink DIR-605L Router

My internet was completely out for 3 days, the modem would not Sync at all. Charter finally came out and said that the Motorola modem that had been serving me great for the last year was bad. The tech replaced it with a brand new Arris TM1602 modem, the new modem seems to keep locking up my Dlink DIR-850L. It drops the wan connection and I have to reset the router to get it back up. Sometimes it comes back up and sometimes it doesn't but the modem seems to be holding sync. I have tried every setting in the modem on the Wan side that I can think of trying. I am using and old Asus router now and will see if it holds. Has anyone else had any similar issues or think of anything else to try? Latest firmware on the router and everything but I am thinking some kind of compatibility issue since these modems are brand new.

What does the router's logs show ?

If your router has a DHCP query frequency setting, or similar, make sure it's not set to anything like "frequent" or "aggressive". My Asus router's default setting was "aggressive" and would cause similar issues. Setting the WAN DHCP query frequency to "normal" resolved the issue.

Thanks for the ideas guys, Zappa I never even thought about the router's logs to get an idea of what was dropping. I don't know why I didn't think of it. Passerby I will have to hook the router back up and check for those settings. Right now I have a $30 Asus router hooked up that I had been using as an extra access point. It has been up for over 24 hours so far on that router so it does look like an issue with my Dlink router and not the modem or connection at this point. I will play with it over the weekend and report back. Thanks for the ideas!