You didn't mention budget so this being STH I am going with the Porsche variant here.
Recommend a high-gain directional antenna by Poynting like
XPOL-2-5G-US - Poynting Tech - Antenna Solutions, South Africa, USA & Europe. Make sure the model fits your local ISP's LTE/5G frequencies correctly. Link here shows a US model, other countries use slightly different frequencies. They have a nice selector. You get what you pay for, a Chinesium antenna can be off-band by 100 MHz and you will never know. Youtube has some videos about Poynting to give you an idea. If you know you live next to the base station you can try indoor omnidirectional 2dBi stick antennae and possibly cheap out.
4m of cabling necessitates more expensive, low-loss, thick, shielded, 50 ohms cabling. Check LMR/CFD 300 or even 400 specs and do not settle for anything much worse. At 600-900 MHz cheaper cabling like LMR/CFD 100 might work ok, but anything above 2 GHz will cost you the entire Poynting's gain lost in the cable (>>0.5dB/m loss at 5 GHz, losses depend on frequency). Make sure you get the right connectors, because RP-SMA is not SMA and not type-N or whatever. LTE stuff is usually SMA while Wifi is usually RP-SMA but double check what you need.
Router Netgear Nighthawk MR1100 is reasonably cheap. LTE only but reasonably priced and speedy LTE Cats. Doubtful 5G will gain you much more speed in 2022. Or the one zer0sum recommended.
A metal rod sticking out of the roof holding an antenna might attract lightning. So give lightning protection a second thought. If the cable is exposed to sunlight, it has to be UV resistant. Service life will then be 20 years easy. You may well find though that you can mount the antenna under the roof i.e. indoors and it will work just fine because of the huge gain being directional.
No affiliation with any of the products mentioned.
