A long time problem with network and Orange TV flux
1 - Pandorabox firmware between master + repeater/relay & no problems with flux TV
2 - Openwrt firmware between master + repeater/relay exactly same config and no TV
3 - Openwrt firmware master + client in WDS mode no problem with flux TV
when connecting two devices via wireless which should be in the same layer 2 network, it's best to run either WDS or 802.11s mesh mode. "repeater/relay" is not a well defined thing, perhaps a relayd configuration is what you're talking about. To me, relayd is a hack and should be avoided (it doesn't work at all with ipv6 for example).
While the configuration appears to be the same, the implementation under the hood can be completely different (proprietary driver vs mac80211).
The behaviour of mac80211 WDS is well-defined (4-addr mode). The same can't be said for the proprietary driver, as the vendor may use a custom protocol.