I don't have any 2330's but I do have a 2630. Following installation it have never disconnected and it is far away from the router. I mean really far and no straight path.
Do you have a dual band router? Try putting it on 2.4Ghz instead of 5Ghz for better range.
Try to reserve an IP address for it. Not static.
Try a less crowded channel. Could be interference from your neighbors' router signals or even other non WIFI devices in your home.
Move the cam adjacent to the router temporarily to see if you get the same issue. In fact do this first. If it is sitting next to the router and dropping out then IMO its defective or maybe even defective in design. If a firmware upgrade doesn't fix it I would contact the BBB and your state consumer AG and hammer DLINK. But that would be the "nuclear" option. Try the other steps first.
Two of my five cams are 2630L and they have been really stable. They remain online continuously while the 2330L cams seem to remain online for only about 10 days give or take a few. They individually drop out, not as a group. Distance doesn't seem to be a problem. Two of the three cams are about 10 feet away from the access point. The third is about 15 feet away.
All cams are already connected to 2.4GHz.
Not sure what you mean assigning IP addresses that are not static. I thought an assigned IP address was static. I've manually assigned all IP addresses. They are not assigned by DHCP.
While there are other signals getting picked up, they are far away and quite weak as this location is in a sparsely populated area.
It turns out that one of my 2630L cams is the one that is the farthest away. The two 2630L cams seem to be quite reliable (1.03 firmware) while the 2330L cams (1.12 firmware) are totally unreliable. As I've said earlier, I do believe that there is a design flaw. I don't know if it is hardware or firmware. If a hardware defect, the question is if they can improve their robustness with a firmware workaround such as a deadman timer in the firmware (assuming that the firmware is still running).