First of all, ALv2 of drivers from the same author of the server suggests that AGPLv3 of the server doesn't affect licenses of client applications.
Also, the blog "The AGPL" helps understanding.
But, I think the license of drivers is confusing in the final analysis, because AGPLv3 will usually supersede/ override ALv2 in case that combined software are distributed or served via network.
The LICENSE section of the older version of the README had mentioned the client license, but had not described the scope of AGPLv3, anyway.
So, I think the README should describe the scope of AGPLv3 directly and explicitly.