iPhone cannot connect to Wi-Fi only when it is WEP

okay, haven't found topic relating issue. if there such thread, forgive error.
problem iphone 4 ios 5 (previous versions had same issue) cannot connect home wi-fi unless:
1, not protected kind of password
2, protrected wep. somewhy router won't accept legit ascii code, hexadecimal.
whenever set protection wpa2 psk, won't find network, , if does, keeps telling me device unable connect network.
have tried forgetting network, resetting network information in settings, far haven't found solution. ideas?

 

which router or wireless access point?

have checked see if there might firmware upgrade it?

b

 

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