Linking a Netgear DG 834G with a WPN 824 v2

I bought a DG834G modem & router 4 years ago but have alwazs struggled to get good reception in mz home due to the thickness of the walls I think.

I bought a 824N router earlier this zear to increase the range but do not know how to link the 2 pieces of equipment or if I have made a mistake and in actual fact should just update mz modem / router.

Please can someone offer advise