is it possible to do a local network between an rv50 modem and a cr6 datalogger (connected through ethernet cable) , to send data to an internet server without using an interface like sc105?
i.e , datalogger ethernet interface = 192.168.13.X , LS300 - RV50 sierra modem = 192.168.13.31 (i guess the default ip of that modem) , and a 4g chip to obtain a public ip through an isp.
It is possible. There are instructions in the RV50 manual.
The ports that the datalogger typically use are 3001 and 6785 (TCP/UDP)?
Its enough for taking remote control of the datalogger? (such as upload programs, etc) ?
remote control of the CR6 depends on how your RV50 is set up and what your ISP connection is capable of..
Look up things like 'public IP' (this is affected by your ISP and the SIM you are using), 'DynamicDNS' and 'port forwarding' (this is a setting in the RV50 which will allow you to 'dial into your logger' from the internet.
Be aware that this is NOT SECURE, do at your own peril.
If your ISP does not have public IP (ususally a bolt on to your SIM plan, if available at all) you can forget about this option right away.
Next up are VPN solutions that need to be supported by either the modem OR the logger.
Logger based: see Campbells proprietary Konect VPN system. Your logger will be reachable via Loggernet and Campbells VPN network. This ties in smoothly with Loggernet, but only capable to serve Campbell gear. Any other Ethernet capable devices on the RV50 LAN (like IP cameras for example or the RV50 itself) will not be reachable via this method afaik.
Modem based: the RV50 supports three non-proprietary VPN solutions: IPsec, GRE and OpenVPN. You probably want to talk to a network admin about your options there if you have no idea what anything of this means.
PS: I'm a user of an OpenVPN based network solution which relies on a part time network admin to maintain and set up (and I like it as it gives me access to other gear inclusive the modem settings). But there are commercial routes you can take, just google 'Best VPN service <protocol you want to use>' and you get plenty options to chose from.
PPS: look out for upcoming VPN solutions like Wireguard (faster, easier to setup/maintain). The RV50 at this point in time does not support this, so might need a different modem-router.