@Carsor Can't be done. You will find if you disconnect the cable you will simply lose internet. If you have fibre, one Deco can become the modem (in some cases), but that's not a good idea as with...

@Carsor As above, how would you get internet to Deco if you disconnect the cable from the device that is acting as the modem?

@David-TP X50 currently at V1.6.3 X50-Outdoor still at V1.2.8 Features of X50/X55 are locked out because X50-Outdoor is added in. Has TP-Link stopped supporting X50-Outdoor or is it End of Life?...

As I outlined above "Probably better to replace E4R with X50 (though even X10 would be 1000% better) and add X50-Outdoor."

@OJS You will lose seamless roaming by trying this. Basically you will lose true Mesh and all the usefulness it brings.

@OJS EAP series cannot Mesh with Deco. You will need to run an Ethernet cable from the EAP to one of the Deco nodes, or Use Powerline adapters (not very stable). Only Deco X50-Outdoor can truly Mesh...