Connecting to Raspi with a RM520N-GL Modem to another Raspi with an RM520N-GL Modem


I have two Raspberry pi with a RM520N-GL and a SIM Card from german Telekom. On the first Raspi is a Webserver. How can I connect the second Raspi to the first Raspi?

ifconfig from the first Raspi:

        inet  netmask  destination
        inet6 fe80::a510:eede:949d:26a1  prefixlen 64  scopeid 0x20<link>
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 1000  (UNSPEC)
        RX packets 9  bytes 1850 (1.8 KiB)
        RX errors 2  dropped 0  overruns 0  frame 0
        TX packets 50  bytes 8554 (8.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Dear @moargusch
Actually, it is related with Raspi, please ask the provider of Raspi.