Two houses two different networks

In my house I have HA running fine on a Raspberry Pi with a lot of devices.
Now i just got internet and an old router at my summer house. I have over there connected to D-link cameras to the Wifi network. When i used them at home I could easily get them in HA with generic cameras but at my summer house I do not have HA, yet, maybe later.
Is it possible to get the stream from the website D-link into my HA at home or in some other way.
I use Tailscale (normal VPN not working, I do not get a public IP from ISP) at home at work and on my phone and it is working goog, can acces HA from these platforms.

So what to do?

I would suggest to set up a permanent VPN link. Not all routers can do that, but you can also use a seperate device for it (i.e. Firewalla). This way, the twoo networks are securely connected and HA can ‘see’ devices in your summer house

I don’t get a public IP address from my ISP so I can not do that, I only get an private IP, it is mobile internet with sim card in router and I am behind the ISP NAT router (I think it is called that).

wan

When you initiate from the mobile device to the VPN host at home, you only have to know the Public IP of your home. Some routers also have a SIM card slot and can handle the mobile connection and VPN connection themselves (for example Huawei B311-221A)

However, you will need to have an unlimited data plan or it will become a very expensive solution.

Use Taiscale. It has no issues with CGNAT used by mobile carriers. There’s an addon.

Good tutorial:

Do take note of this though:

I use Tailscale on my HA at home already but I am not sure if I can use it with my old Dovado Router at my summer house. I doubt it is supported.
Right now I only have the router and two D-Link WIFI-cameras nothing else.

Oops. I skimmed that bit in your post sorry.