Question about ZTE MC801A HyperBox

Port forwarding problems with the ZTE MC801A ------------------------------------------------------------------------------- I bought the ZTE MC801A router because it was previously not possible to contact the heat pump company's server with a heat pump gateway that was connected to the WLAN network of the 4G router I was using before. This would be necessary for remote control of the heat pump via the internet. According to the heat pump company, certain TCP ports must be open for the gateway for this purpose, which could be made possible with port forwarding on the router. Because the MC801A router allows port forwarding, I bought it from Digitec. The router works perfectly with my WLAN-connected devices such as notebook, iPhone, iPad and other devices. The heat pump gateway also connects to the Wi-Fi network of the ZTE MC801A router without any problems; unfortunately, the gateway is still unable to connect to the heat pump company's server. Although I had correctly entered the port forwarding rules for the required free ports of the heat pump gateway in the firewall setup of the ZTE-MC801A router, the corresponding ports were not opened. After some googling, I found out that, according to information in newsgroups, port forwarding with the MC801A router only works if either the router is operated in bridge mode or a public dynamic IP address can be provided by the Internet provider. Hence my questions to the users of the ZTE MC801A router: - Has anyone experienced similar problems to mine with port forwarding or has anyone successfully managed port forwarding with this router? - I could use the ZTE-MC801A router with a SIM card from Galaxus or Salt. Does anyone know if you can get a public dynamic IP address from Galaxus or Salt for the respective SIM card?