Recently, I had to upgrade my router (old one was 6 years old…), and since that time, I’ve had issues with camera “disconnections”, or simply not being available. Sometimes I couldn’t access the camera on my LAN, so a power-off reset of the device was necessary. But lately, I’ve been able to connect to my camera on the LAN, but couldn’t remotely. The two conditions split nearly evenly.
The power to my house is questionable whenever the wind is high (I live in Kansas, on a hill, with no real windbreak - so guess what?) So I had a whole-house surge protector installed several years ago (probably time to replace it as well). While a UPS was on my wifi-router, the power may go down long enough for the router to lose power (and I had to replace that UPS about 3 weeks ago too - old).
Anyway - I believe the problem is a DHCP problem. From the device, we cannot specify the IP, so it relies strictly on DHCP leases. With cameras going up and down, and possibly the router, there may be issues where the camera didn’t go down (maybe you’ve done a router reset, or have it automatically reset once a week, etc.) so it still has the IP address. BUT - the router has lost the list of DHCP leases - so some other device might get the IP address. Maybe the router detects that issue - maybe not. Or, the device might have lost power (no UPS), and comes back up (along with several other devices), and DHCP leases get borked (I’ve had experiences where not EVERY device goes down). So, we may have several conditions under which this might occur, and get the camera confused until you do a power reset of the camera device, as it’s IP has been given to another device. (I also had a similar problem with a wifi printer).
To solve the problem I’ve created DHCP reservations for the MAC addresses of the cameras and printers. Where they were losing their connections every 3-6 days, I’ve now gone 3 weeks without issue. So - if you’re having problems with connectivity you might go into your wifi-router and find those camera MACs in your DHCP leases, and give them an IP reservation so no other device gets that address.