@_PJ Hi, I had a simlar problem when I was trying to aggregate a lte and wifi bridge (our local ISP offers internet via a long range wifi link) connection with a er605, the problem is you havent got a true aggregated connection you have got 2 different connections each with its own ip address and so if your trying to log into a website it might use either of those addresses at random.

So far the only soloution I have found are that you need to do is to either enable Application optimized routing (then the er605 will always allocate the same connection to the device) this shares out the 2 connections equally accross the network, so its not aggregating them unfortunatly.

I am currently trialing a VPN connection betweeen a remote location (LTE and Wifi Bridge) and my main site (Fibre) using 2 vpn tunnels and so far i'm having mixed results but the end site is then using my main sites internet connection and bandwidth, this is a solution for me as I have multiple sites but i beleive there are services you can subscribe to that offer a simlar experiance so you'd connect your 2 connections to the same aggregated vpn provider and then the provider would combine the connections for you.