wireless with router or pc

Ok, i really need to get this to quit.. HELP

have multiple devices on a home network. use cable modem to a router, which offers me dual band wifi along with guest network which almost never gets used. i have macs, old pc, phones, etc on it. up until recently absolutely no problems. then it all cam crashing down. Recently have had to get new new modems..long story. had them provisioned each time and stupid phone rep screwed it up. Finally got back inteet...reprovisioned modem..all seemed fine, but now i keep having issues with network. 1- recently had pc upgraded to solid state and keep only windows OS (7) on it. i use old hardrive for storage...hardly use the computer, but need it for older software that i refuse to update...basic use only now i had to reset everything and got the router (netgear r700 nighthawk) going again. modem seems ok...but more often now i keep getting ip address conflict. i dont get it...i typically release the ipconfig on pc and restart...to avoid another conflict, bec restarting doesnt always clear the conflict. i looked online at the router config. some info i see: 1- old pc, which keeps conflicting with my mac shows connected to the 2.4 band on router. it has IPv4 connectivity. slow old thing, but network card that fit only had this speed. My mac has 5 band speed connectivity. so although they are on two different bands, we still keep seeing conflict. 2- i can see all the devices listed...they are (right now) not in conflict. i see diff mac addresses...everything looks good 3- sometimes when the computer may be in sleep mode, but when comes on it is in conflict...dont get that.

ok...if the IP address is REQUESTED by each device...wouldnt that mean soemthing is up with computer reqeust..or would it mean that router isnt working properly. i do have the latest firware update...made sure its the good one, bec i understand tehre was a bad one previously so good there. Could this be issue with old pc computer and the add in of the solid state drive? i mean everythign is still on harddrive...or maybe the question is WHAT PART OR THING IN A DEVICE REQUESTS THE IP address from router? maybe if i knew that it would help..or has someone got a suggestion

ISP provider- mediacom neatger r700 nighthawk dual band router various devices..mainly use mac with latest version of El capitan old pc is windows 7, nothing special..with the two drives i mentioned. all updates are down. modem is arris SB 141..

HELP! PLEASE

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