Looks like the SSLv3 cipher is not included in Teltonikas standard libopenssl (or similar, like wolfssl) . Which is no wonder, because being considered insecure, out of favor for a while. That is the bad news.
The good news is, you have a RUT955. Which runs "official openwrt" , giving you many more opportunities to customize your system, compared to Teltonikas stuff.
I am running a large fleet of RUT955, having custom openwrt firmware, with lot of custom code, for mqtt to AWS-IoT, remote firmware update OTA, remote access via VPN, data queuing, unattended remote configuration, ModBus/RTU to lower level sensors, auto-switchover between wan/wwan/wifi etc. Only makes sense for a lot of devices, of course.