New iPad can't connect to 2.4GHz router network, only TC wireless 5GHz network

Hi guys, I actually have a Wi-Fi nithgmare with one of my New iPads.

Sorry for my poor English, It's not my main language.

I have two 64GB Wi-Fi New Ipad, we bought them at same day.

It was all marvellous until the last weekend when I had a problem with Splashtop Streamer app because the installed iPad app was old and it crashed the iPad wi-fi 2.4GHz connection comming from a WR2543ND TPLink router.

What I did: I set the TC to create a new network and tried to connect the iPad to this new network and the iPad finally could access internet.

The problem now is that this New iPad RECORDED that the 5GHz N BAND was the best connection and it denies the router 2.4GHz connection, I even can login but I can do it as always did with my other New iPad that never had connected to 5GHz N BAND network.

I need the 2.4GHz TPlink router connection when I go far from the room and that signal is better than Time Capsule N BAND signal ( TC G BAND is weak compared with TPlink signal that uses huge three antennas). Sometimes I can connect on 2.4 GHz when I place the iPad near the router but it's really rare and usually the connection drops after minutes.

I made all common suggestions like: RESET the iPad network configurations, I RESTORED the iPad software to EMPTY factory settings, I turned off/on after forgot the connections, I upgraded the TPlink firmware and restored all settings manually, I spent the last two days on it.

The facts: my 2nd New iPad can connect smoothly to TPLink network as both always did, but my other New iPad can connect ONLY TO TIME CAPSULE AND TP LINK ROUTER 5GHz N BANDS. The New iPad can find the 2.4GHz network but denies the (WPA2/PSK and AES security) login tries.

I'm afraid to connect the 2nd New iPad to the TC or router 5GHz N BAND network, because I suppose it will MEMORIZE the N BAND ONLY status and can deny the TPLINK 2.4GHz signal forever.

I can graphically view my local wi-fi signals using a mac app and there's no external wireless network making interference on my network. I manually set their main frequencies to unused zones.

Please if anyone can make any suggestion!!

I was very disappointed with this situation I call as a Apple "trap"... it looks like the iPad knows that I have 5GHz N BAND and force me to use it instead of 2.4GHz slow but still long-range network. Maybe my iPad antenna was broken, or my MBP saved any information about my network config and devices settings I dunno, it's very hard to decide to make a test with my other New iPad and see two new iPads going to wi-fi nighmare forever 😟