Hi Sorry about the cats and other stuff sent ,message on phone after a beer !! .
The antennas you have are not great they with have arround -3db and have an impeadane of 25-35 ohms have no matching network to make then 50ohms, are helical so can have a weird radiation pattern, but small and can be good for short range. You can adjust a bit the resonant point altering the length by compressing or streching first . The first part of the coil act as a sort of matching/ counterpoise and the second part more the radiator.
You can can cut the lenght to trim but a once of activity. I have these antennas but only use for testing on the bench.
For installed applications I use the antenna I sent pictures of before like this https://www.ebay.co.uk/itm/5dBi-868MHz-Wireless-Antenna-Router-Antenna-RP-SMA-Female-to-IPX-1-13-Cable/112984385477?hash=item1a4e64e7c5:g:ZyUAAOSwKjha890C . These do not have 5dbI gain but more tlike 3dbi but can be made to match well if modified as picture. The Chineses antenas they makecover many bands e.g for GSM/ 868Mhz/ 4G and 915Mhz they suit none of these hence the need to modify . The black sheild BTW just pulls off. This type of antenna is call a sleaved diople , the coax runs up a metal tube, that acts a a balum for the antenna and it matche the low impeadance of the radiiating element . An alternative is a 1/4 wave diople mounted above 4 radial pointed down at 45degrees this matches the radiating antena to 50 ohms and hence a good performance. with a gain of 2.14.
The other antennas, I have used are https://connectedthings.store/gb/sirio-gp-868-c-lora-gateway-antenna.html very good., but pricy. I have used Sirio antennas professionally for years always very good .
Hope helps just ask for more info if you need it.