Hello,
Based on Quectel EG06 documentation, the modem in RUTX11, it is capable of aggregating bands B2+B13 and B4+B13. However, the usage of additional band depends on the signal parameters of that band. If the band 13 has low signal quality, it will not be used. If your current router supports manual band setting, you could test band 13 by setting it yourself and evaluating the performance. Reference parameter values are provided in this link: https://wiki.teltonika-networks.com/view/Mobile_Signal_Strength_Recommendations#4G_.28LTE.29. This might help to decide, whether the hardware update is necessary.
Regarding your question about CA description meaning, B2 itself means not a single frequency or a channel, but a range of frequencies, 1850 - 1910MHz for uplink and 1930 - 1990MHz for downlink in particular. These bands can be further divided into channels of 1.4, 3, 5, 10, 15, 20MHz width. Thus, B2+B2 simply means aggregating a couple of channels within the same frequency range.
Best regards,
Žygimantas