Create a half-cylinder shape with aluminum wrap. Place it behind the antenna and adjust so that the antenna is at the focus point. Check signal quality while you adjust positioning for both antennas. Also, try increasing transmit power from the router if possible and choose the channel (frequency) with the least interference. If done right, the signal can go through several walls and ceilings.
As i said before I played for long with those hacks, they are nice and userful but now I need a better solution, I can't keep the antenna inside (too much signal loss) and I can't keep the router outside ( is not hard waterproofing it but it will result very bulky and I can't power it over eth)
I think that an adapter like the one I've linked is a far better option: PoE (so just one cable) , waterproof, booster integrated, antenna and small form factor ...I just need to know if someone have ever tried a similar product
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Btw looking for the channel interference it's a good suggestion, I've found a nice android app for wifi monitoring and this evening I'll try to find the most efficient channel
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