This topic has been covered on this forum before. See here. Don’t assume your antenna is good, just because it was made for IN865 - test it OR purchase from a reputable manufacturer.
Real-life example: when I needed flexible antennas for US915, I took my sensor vendor’s advise and purchased 2J-antennas model (qty 40 of part # 2J5115P-915 was ~$200 + $90 S&H via DHL; comes to ~$7.25 each) instead of much cheaper antennas (~$1/each + ~$8 S&H; cost of $1.25/each) from ebay, but of questionable performance and worries.
I briefly considered purchasing a N1201SA , but decided that 1-man project had enough complexity already: I borrowed one briefly and while it was easy to use, it required ~1 hour for each antenna to connect, measure, modify/adjust, and then patch up external appearance to not look too crappy; realized that $7.25 each was actually a GREAT BARGAIN 