What Type of Antenna Connector Is This on My LTE Modem? (Photos Attached)

I have looked everywhere (scouring the internet and through the manual of the device) trying to find out what kind of connector this is. I have been unable find out what kind of connectors these are and I am hoping that someone here will be able to help me out. I have the pictures of the connectors attached. I'm trying to direct someone in purchasing an antenna for their LTE modem but I need to be able to know what type of adapter to use for this connection. Any help is greatly appreciated. Thanks!

Hi Aaron-Can you take more pictures off to the side a bit of both ends of the connector so we can see the threads (or bayonet) a little better?  It almost looks like a BNC, but I suspect that's not it.What's the make and model of the modem?  We might be able to find it that way.-Rick

Aaron,According to this  web page,
https://www.air802.com/connector-identification-chart.htmlit could be a TNC connector.Best to check the dimensions to be sure.Elizabeth

Aaron it does look like a TNC as Elizabeth says, and she's very rarely wrong :-)As Rick says, a side view would help, and some idea of scale (photograph it next to a ruler)
Beware - they make TNCs in dual genders - ie male and female plugs and sockets - so make sure you get the right thing!  (Elizabeth's web page link shows both types.)  Yours appears to be the normal type , not the RP (I think that means Reverse Polarity) type.PS Elizabeth - great resource - thanks!

It is very difficult to identify. But, I think it is a TNC connector. Can you please share more pictures.