Ok I understand see what you mean on IVS, yes it removes IVS capability from the CVI cameras when you add IP camera capability, but IVS still works fine on the IP cameras.
I can view anyway I want, this shows 1 IP camera top left, the others are CVI
View attachment 98519
Sorry for the delay,
i have to test with a NVR before reply ( and it's cost money

)
so after different tests :
1 - you're right, we can use an XVR and it's OK, just you can't use IA for IPcam but without this all is OK !!
But when i connect my 5 IPcam, the XVR show me on my tvscreen juste 3 of them ( the rest is black screen in multi-screen, show me the image only when full screen), so at this moment i thinks it's a problem with the XVR
BUT not !!
2 - i bought a NVR 2208-I, it's really better because i can use IA fonctionnality for my VTO !! instead of the XVR which it can do that only for Analog cam
But i have the same problem, only 3cam and the rest show a black screen... if i open a black screen ( the 4th ipcam for exemple) i can see correctly but in multi-screen i can't see more than 3 cam at the same time... maybe the network bandwitch but i have 5 ipcam and it's create for 8
on the smartphone, i don't have this problem...
for information i have :
2 ipcam dahua 4k
2 ipcam dahua 2k
1 VTO dahua 720p
At all, to respond to my question, and like BIGREDFISH said :
use XVR for IPcam is totaly OK, just you need to know if you want to use IA of the XVR is only for analog cam and if want to use IA for a IPcam which don't already have IA function for exemple, you need to have an NVR