Screen sharing with shared Wi-Fi

Do my dad is in his 90’s and living in a senior apartment with my old iMac on High Sierra. He used to have his own Spectrum account, but now uses the facilities WiFi (still Spectrum). I had been trying to use Screens 5 (which I really like) to help him as I had in the past with another screen sharing software, but am unable to connect or even install his end of the software due to a firewall (I assume).

I think I know the answer, but is there some way to connect to his Mac from outside to help him? I tried to have a local friend poke at some ports, but after calling Spectrum, determined that he does not have an internet account, but just has cable and the shared WiFi. I am looking into how much it would be to add internet to his account, or give him a minimal cell phone and HotSpot into his computer. Maybe someone has solved this with a similar situation but I can’t see how to fix it with a simple solution. Obviously they cannot open the WiFi with UPnP as that would make everyone vulnerable. Screens5 mentions Tailscale, but I am not sure what that is or if it would address my problem.

If Screen 5 doesn’t work, I’m not sure if RealVNC Connect will, but you can try it for free. I’m sure there are lots of other, similar solutions, but RealVNC has been around for a long time.

I’ve had a good experience with it. It has a “server” or “managed device” component that you would install on your Dad’s computer, and a “viewer” or “technician” component that you would install on yours. It’s free for up to five servers [1]. I’ve used it for years to support my now-94-year-old mother-in-law. (I have no affiliation with them; I’m just a satisfied user.)

They make it hard to find the free plan, but sign up for the free trial:

Our free trial lets you try out the features of our Premium plan for 14 days. For the trial, you’ll be limited to adding 10 managed devices and 1 technician license for On-Demand Assist.

Then, when the trial expires:

Once your 14 day trial ends, your account will revert back to our Lite plan which is free for non-commercial use and is best suited to personal projects or lending a helping hand to less tech-savvy friends and family.

When I signed up (years ago), they had a free version, and I just downloaded that, created a free account, and have been using it ever since. You may (I’m not sure) need to give them a credit card for your “subscription”, but if so, and if you want to stay free:

By default, your RealVNC Connect subscription will renew automatically. If you don’t want to renew your subscription, please turn off auto-renew from the Billing page of the RealVNC Connect web portal.

(Quotes are from the FAQ section at the bottom of their pricing page.)

One usage hint: When viewing your Dad’s computer with RealVNC, at the top center of the viewing window there is a couple-of-pixels-high area that, when you mouseover it, drops down with some buttons to manage the window.

[1] The free trial lets you have five “servers”, but when you revert to the free plan, I think the limit is 5.

I would shop around for a used mac that could run a current supported OS and use TeamViewer. TeamViewer uses outgoing connection (to TeamViewer servers) on both ends to set up the connection. If TeamViewer can’t connect over port 5938 or 443, then it will try on TCP port 80. TeamViewer is free for personal use at home or helping friends and family. I have used it to support users working at home during Covid-19, and to support my 90 years old mother-in-law. You can set up your father’s TeamViewer to start on boot of mac and with a password that is known to you.

Can you try to create a Tailscale network? I’ve recently succesfully used it to create a network that completely ignores a firewall. It is relatively simple to set up, and very simple to add machines once you’ve done so.


Isn’t there a way to screen share with Messages?

I use AnyDesk for client work, Mac to PC, so it should easily do Mac to Mac.


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The usual problem is the “sharing” Mac needs to act as a server, but you can’t reach its address and port from outside. You need a solution where the sharing Mac reaches out to find your computer.

Some suggestions:

all of which are free for personal use.

I use TeamViewer for similar support. I have TeamViewer set to always run as a host; this makes it easier to connect because it doesn’t require action by the sharing user.

TeamViewer was the program I used previously. I thought they had dropped the free account, so was not using it. I really liked their remote connect that could be activated simply by installing a self running program and then just reporting the numbers shown to allow access.

I will try that again and consider installing the main program in his computer to always be running so I don’t have to ask him to run a program each time I need to connect. If that does not work, I will try the Tailscale option. Whatever that is.

It may also have been that the current version of TeamViewer would not work on his older system.

How are these programs different from Screens 5 type?

I don’t find the free version of TeamViewer on their website. Is it just one you Try and then just use and it doesn’t bill you or bug you? It would only be one connection for me

The problem here is that many of these systems will not work with MacOS 10.13. :slightly_frowning_face: tailscale needs 10.15 or higher. All good suggestions

Download TeamViewer from or Empowering personal use for free with TeamViewer Remote.

Looking at the TeamViewer site…

It looks you can use TeamViewer version 12 - 15.19 with macOS 10.13 (High Sierra). The current version is 15.52.3.

You can download previous major versions, but I don’t see a place to download previous minor versions of a major version. For example, to get version 15.19.

And here’s where you run into trouble:

  • TeamViewer doesn’t like it when both sides are running different versions. It may not allow it at all.
  • What happens if you install version 14 as the host, but version 14 doesn’t run on the controlling Mac? For example, macOS 11.0 (Big Sur) requires version 15.12 or greater.

This is where something more primitive like VNC wouldn’t have trouble working across wildly different OS versions, but then you’re back to the firewall (or just NAT) problem.

This is my experience. It is highly unlikely it will work.

And with High Sierra on both ends, which might be possible via virtualization, I seem to remember you will get a lot of nagging to upgrade, which can be confusing for some.

TeamViewer did lock many people out quite a few years ago, for “commercial” use even though some were doing personal sharing (like what you are doing)

I’m on Sierra and AnyDesk is working fine.


Is there a free or cheap version of Anydesk, or is it geared toward businesses? It may be a solution for me…

They do have a free version with limited options. I’ve never been able to get the remote print to work, which does work when I use Splashtop or Microsoft Remote Desktop. But file transfer works fine.


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I remember that. I was using the free version to support my mother-in-law at the time and I got messages from the app where I had to reply that I was using it for personal use. This happened when I was at work. At home, I did not get the messages.

I never got locked out, although I got the message at work for several years.

AnyDesk works the same way as TeamViewer as far as I can see from their documentation. So if it can work with High Sierra it is a better choice.

Screens I could never get to work reliably despite all the praise I read about it.

Jump Desktop worked straight off and is what we use now. It’s excellent. I help my mother as well using it.

Will any of these mentioned apps (TeanViewer, VNC, etc.) wake up the remote computer (unattended) that one is trying to access?
I’m mostly out on the field trying to access my home computer with my laptop, but unless somebody is home to wake up my computer and accept the connection I cannot connect.


That’s a whole other problem.

What you need to do is have “Wake for network access” turned on, and then send a Wake on LAN magic packet from the Internet to the remote machine. There is a website you can use to generate and send the magic packet.

The difficulty is getting a home router to pass the magic packet to the network.

I’ve heard that some routers let you connect to the router from the WAN (Internet) side, then use the router’s admin interface to send the WoL packet to a connected computer.

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Thanks Michael…looking into magic packet as we speak.