The purpose of this model is to access the internet via LTE. With the availability of fibre optics, this becomes obsolete. The new modem provided can then be connected upstream of the Zyxel and this can then provide WiFi in router mode.

https://support.zyxel.eu/hc/de/articles/4403365084818-Erweiterte-Downloads-f%C3%BCr-5G-Ger%C3%A4te

I switched from a 4G Asus LTE router to this Zyxel 5G. I have been completely thrilled with it for over half a year now. Top speed; reliability without reproach. I can only recommend it. I can't say anything about the consumption - I've never measured it.

Hi, I use a Poynting XPOL-2-5G outside the house and pointed at the transmitter. I get the same reception power as if I put the router outside. Greetings. Michael

Hello, I've only run the router with Sunrise so far and it works fine. (But I think Sunrise is on 3.5Ghz for me). When I'm in the country again, I can also test my prepaid Swisscom. I wanted to compare anyway. However, in my opinion the external antenna is not suitable. Internally, the router already has 4x4 MIMO with 4dBi and now you are replacing that with 2x2 with 3dBi. I have tested a similar external antenna with 2x2 and 9dBi and it was a little worse than if I put the router itself in the same place on the balcony. Try testing the router yourself in the fresh air. (where "your" transmitter is, do you know?) Greetings from Bavaria. Michael

as an approach... I operate the router with a DualSIM from Swisscom (the main SIM is in my mobile). Works perfectly. I can't guarantee whether it will work with a MultiSIM from Digitec, but I assume that it will...

No Nebula that I know of. I assume the larger NR5101 has a better antenna layout, allowing better reception. Ours stopped recognizing the SIM card, but after an exchange it has been working fine and delivering good bandwidth.

Yes

According to the manufacturer, the following features are listed: NAT support, NAPT support, VLAN support, Stateful Packet Inspection (SPI), protection against DoS attacks, ALG support, MAC address filtering, VPN passthrough, URL filtering, IP address filtering, firmware upgradeable, support for Wi-Fi Multimedia (WMM), Auto Channel Select (ACS), Wi-Fi Protected Setup (WPS), DHCP server, hidden SSID, port server.Wi-Fi Multimedia (WMM), Auto Channel Select (ACS), Wi-Fi Protected Setup (WPS), DHCP server, hidden SSID, port forwarding, reset button, port control, Firmware Over-the-Air (FOTA), VoIP support, Internet Control Message Protocol (ICMP), dual band, router mode, DMZ support, DynDNS, bridge mode, 4x4 MIMO technology, MQTT support.

According to our supplier: Since the router has 2 SMA connectors for the external antenna, any antenna that supports this connector :)

2 Delock LTE/HSPA/GSM antenna, SMA connector