I found a solution. To anyone having this problem : it’s quite easy and stupid, I don’t know why I didn’t think about it earlier. I changed my DNS in my Archer AX-50 DHCP. They were unset, so the router was using its own DNS mechanism. By setting them to my ISP ones (which will be used by the Archer in fine) this bypasses the rebinding protection mechanism.

  @Kevin_Z Thanks. Nonetheless I still think this should be an available setting. TP link routers of lower grade than the AX-50 can be flashed with OpenWRT and OpenWRT does have a whitelist setting for DNS rebinding protection. So I'm pretty confident that this could be implemented in a next firmware upgrade. To be honest, if OpenWRT were available for the AX-50 I would flash it without a doubt, because it is kind of frustrating to have some non tweakable and non documented perks implemented !