Powerline AV1000 not connecting to existing powerline network created with AV600
So we just changed our internet provider and the main adapter connected to the router as the start of the powerline "mesh" is from the TL-WPA4220 KIT. The adapter that was part of the set has connected without issue and is providing a consistent and reliable connection via ethernet to my PC. However, another member of my family has recently got a PC and so we needed to get another adapter. That was when we got the TL-PA7017 KIT which offers a higher connection speed than the original kit. I understand that the powerline network will not go above the lowest adapter in the network which hasn't become an issue at all. However, since we changed internet providers, the TL-PA7017 KIT will not connect to the main adapter linked to the router. When I open the TP-Link Utility app, there is a red line with a "?" going from the main adapter. Resetting each adapter has not fixed the issue and I have reset the PC's networks in an unsuccessful attempt to see if the issue would be resolved by that. Is there something that I have missed? If anyone can assist that would be amazing!
Thanks in advance,