Questions about Ubiquiti EdgeRouter 4

Yes, works wonderfully for me 👍

In general, third-party routers can be used on a Swisscom connection, but they must have the ability to set the dhcp-client option 60. With the edge router, this can be done via the console using ssh. Operate it this way on fibre. On a DSL connection, however, you also need a router with a DSL modem, otherwise it won't work. The only one I know of is the Fritzbox and as far as I know it is not configured for a business connection. For DSL, I would advise you to use the centro Business with PPPoE passthrough. Then you can add whatever you want to it UDM/edge/pfsense etc...

You can set up a VPN on the router, for example OpenVPN see documentation: https://help.ui.com/hc/en-us/articles/115015971688-EdgeRouter-OpenVPN-Server I tried it once and have to say that the performance, i.e. the speed of the VPN, didn't knock my socks off and I would only use the router for remote access ala I still have an account and not as a VPN server for all traffic between two offices. I now use my NAS for VPN with high performance. Wifi should not be a problem if you configure the existing device properly before plugging it in. You can use the EdgeRouter for DHCP and routing, for which it works super fast and extremely stable, and turn off all these functions on your existing device but still keep the WiFi access point on the network.

I don't know anyone with GGA Maur (yet). I've been running it for 1.5 years with Init7. No problems either when setting it up or during operation.

The router has only one SFP port (no SFP+) and therefore supports 1 Gb/s at most. For Salt fibre you need a router with SFP+ and 10 Gbit ports and a compatible SFP+ module. Unfortunately with Salt everything is proprietary and no documentation is available. But to improve the wifi only, it might be enough to connect a wifi access point + PoE adapter.

Yes the device is suitable for this. L2TP Ipsec, pppoe. You can do almost everything with the EdgeRouter4. But you have to be aware that only the basic settings can be done via the web interface. Many things have to be set via CLI. I2TP as an example. You can find information at ui.com/support. Read the manual there and have a look at the configuration examples. There is also a large English community for the Edge products. If you don't know anything about CLI, it will be a challenge. Perhaps the unifi usg / usg pro / dream maschine pro would be the better choice, as everything can be set via the controller software. Take a look at the data sheet for both products and compare.

Attached is a picture of the back (sorry, only found a picture with the rack mount shown): https://www.handymanhowto.com/wp-content/uploads/2016/11/Ubiquiti-EdgeRouter-4-Rack-Mount-Kit.jpg

No, this is not possible because there is no DSL modem installed.